Hi brandgirl, and welcome to the forum.
You said "I've tried to end the relationship 2 other times and both times he BEGGED and PLEADED me not to leave him. Promising change, therapy, etc. Each time (including now) there is some new epiphany that explains the problems in our relationship and that he is convinced that with the changes he's "committed" to, things will once again be perfect like they were in the beginning. He sobs and cries, says his life is over, that he's losing his world if I go, etc. Begs me to help him through the therapy and to be there for him...that with my help he can get through this and be the man I fell in love with again and that we'll be happy forever...etc. 2 unquote
You have decided that you want to end the relationship, your mind is set on it, and you are entitled to do so without justification to anyone. You're a human being with free will and autonomy. By reacting this way he is denying you freedom of choice, imposing his needs and will upon you and cajoling you into doing something you don't want to do. It is a covert sort of control. He is also manipulating you as he is playing upon your guilt and sense of duty. He's also putting the responsibility for his emotional state upon you and not owning it for himself or taking responsiblity. No one can help him through the therapy, but himself, that is the whole point of therapy. He is not accepting reality and is displaying signs of neediness, which is a sign that he could be very emotionally immature.
Y ou said "This time is no different, except that I have realized this "emotional manipulation" thing. Obvioulsy the first 2 times, I stayed and agreed to help. I stood by him and coached him through the rough times, tried to work on the changes he promised etc. But within a few months, I'd catch him in another lie, which he'd then proceed to downplay, say I was overreacting or misunderstanding, etc."
You don't know when he is lying or telling the truth. How can there be trust in this relationship if he lies? By downplaying the lies, once again he's denying responsibility, and by downplaying your own quite reasonable and normal reactions to them he's gaslighting you. Gaslighting can be very dangerous as it causes the victim to doubt their own reality, perceptions and thoughts, and the perpetrator can then use the victim's doubts as a leverage for control in the relationship. It is very common in abusive relationships and a real red flag.
"So, here I am again at a crossroads. In light of learning about the emotional manipulation, and that it's real, I KNOW he won't change, and that I need to leave. But it's SO hard to listen to someone you love crying and sobbing like that. I get texts and voicemails from him all day...saying how miserable he is." unquote
Yes, it can tug at a person's heartstrings to see their partner crying in this way. However, if you have decided that you really do not want to be in this relationship, then you can't sacrifice your future and your life at the expense of someone's emotional reactions. This would lead to long term resentment, and would not be fair on either of you. You would each be depriving the other one of finding true happiness in the future. This lifetime that we have will never be repeated. It is not a rehearsal. It is too precious a gift to waste upon lost opportunities. Just as you have to own your emotions and responses and make them your own, so does he. He alone has the power to make changes to his emotional state, and you are not responsible for it. If you get concerned that he may harm himself in any way, then you need to tell the police. You are not responsible for his reactions and never can be.
You said "I'm an extremely emphathetic person and hate to see anyone I care about hurting. I realize that's part of the problem. I just don't have it in me to be cruel and completely cut him off. He's also been MY world for 2 1/2 years. I don't have many friends or family in the area, but I can't move because of my kids. So the thought of being alone really scares me. I'm 40 and don't want to be alone the rest of my life...I don't even remember how to date anymore, and I really think I'd have a hard time trusting anyone again...let along fall in love." unquote
You gave him a gift when you showed him concern and empathy and kindness. You sound like a lovely person and you gave him the gift of who you are. This is a gift that should be treasured for what it is. You should not allow this gift to be used against you as a leverage for him to control you by manipulation. In a lot of bullying situations, the bully uses the victim's good nature and politeness against him. He may not be intentionally bullying you but he has gained some control of you in that you're forced to be in a relationship you don't want to be in, forced by the fact that you're empathic, caring and polite. He has also been your wold for two and a half years, and it won't be easy to part. You will grieve for what might have been, grieve for the person he could have been, grieve for the good parts of him,grieve for the relationship itself. I have been in the same position as you hun, and I was scared to part with the guy because I knew that if I did I would have to experience all of the emotions of grief. I can see where you're coming from. It can also be very scary to be alone, and if you're isolated with very little support it may seem safer to remain in the relationship. This can be a real quandry, and the fact that it's not a decision to be taken lightly can cause a great deal of confusion and uncertainty. It's almost like a "damned if I do and damned if I don't scenario". I can identify with you on this one. Your situation is so similar to one I've been in. The great unknown can be scary. The thought of loneliness can be scary. So can the idea of lost opportunities and always wondering about what might have been. No one can decide this for you. You have to decide yourself. You say that at 40 you don't want to be alone for the rest of your life. 40 isn't old. You could have another 50 or so years left,or more, which is highly likely as people are living longer these days. This means that you're probably only in the first half of your life. However long a person lives, their lifetime is a gift. I'll repeat that. It's a gift. It's rather like a blank canvas to paint any colour they choose. What they choose to do with their life is up to them.You say you don't know how to date any more. Each new person who comes into your life comes into it like a blank screen. There are no rules. Each person in a new relationship makes their own discoveries on a daily basis. Each new relationship contains dynamics that are completely unlike any previous or subsequent relationship. Remember when you had your first kiss? You were unsure and uncertain at first and then it all fell into place. It was the same with your first relationship, and every other relationship you've had. You say you'd have a hard time trusting again. This can actually be a good thing, for it means that you will put certain safeguards in place to prevent you from being taken for granted or hurt. Trust comes gradually. It is built. It should not be any other way. You say you don't know if you'll fall in love again. Who knows? Maybe, initially you need to learn to really love yourself, and build up a relationship with yourself, discovering who you are. This can be a good foundation from which to build upon and can be as infinitely rewarding as falling in love. Discovering who you are can be a beautiful journey. You can be anyone you want to be.
Therapy can help you to make some sense of your situation and help you to give yourself the right answers.
I wish you well.