Grieving over lost relationship

My boyfriend of 1 1/2 years, with whom I had a wonderful relationship, suddenly decided to go back to his ex-wife of 23 years. They have been divorced 5 years and she has never gotten over him and moved on with her life. He initiated the divorce because they fought constantly and she was verbally abusive.
He still loved her but he couldn't deal with all the turmoil.
So then he meets me, and we instantly hit it off. Over the course of a year and a half, we grew very close. We never fought because we are both very easy going, and we shared tons of great times. We really were happy together and we were close to getting married. We fit like a hand in a glove....everybody said so and we both agreed.
I knew that his ex wife was very jealous of me and that she was meddling in our relationship a lot. She appealed to his guilt and sense of obligation and did a lot of manipulation.
anyway, I never thought anyone or anything could come betweern us because we were that close, best friends even.
She knew we were getting more and more serious so she suddenly stepped in and told him she couldn't bear to lose him and that she wanted another chance with him.
This threw him into mass confusion because he was (and still is) deeply in love with me, but he has always felt very guilty about divorcing her because they had a very close family---4 kids and now two grandchildren togther.
So he came to me about a month ago and told me that he had to give the relationship with her another try although he knew it probably wouldn't work out.
He basically asked me not to give up on us, that he was pretty sure he would come back to me. We cried together and he pleaded with me not to turn my back on him.
He still wants to maintain contact with me and he says he never wants to lose me. I told him what he did was taking a huge chance on losing me.
I was absolutely devastated when this came down with no warning a month ago. He still calls almost every day to say hi and we have seen each other maybe once a week...but no sexual contact. I have poured out all my grief and anger to him, and he tells me over and over how sorry he is and that he still loves me deeply.
A few days ago, we had a long talk and he told me that they (he and his ex) were sort of going through the motions and that he felt a lot of healing was taking place between them, but in his heart he knew that it was not going to work out and that he wanted to be with me. They are already fighting now. He told it it was only a matter of time before he sat down with her and told her it was over.
Anyway, I have been grieving horribly and can barely function. I am devastated that he is with her. I know he will probably ask me if he can come back---but a lot of pain is there for me and he broke a very strong bond between us. I have saught out counseling to deal with my depression and grief. The weekends are the worst....I am too depressed to go out and do anything, so I sit at home and suffer. At least during the week I am busy with work.
I know I need to stop contact with him for now, as it is unhealthy for me and causes me a great deal of pain. But the thought of no contact causes me a lot of pain too.
He did a terrible thing to me, I know...and it was very wrong and selfish of him to do it. I know he is sincerely sorry and he doesn't want to see me in pain. He is actually a really good and honest man.
His reason for going back to her was mostly guilt, and she feeds into it.
I know i should just move on with my life for right now and start healing...I have not even begun to heal, I am still in shock and devastated over what happened. I still can't believe he did it.
I am stuck in a pit of emotional hell right now, my emotions range from despair, anger, depression, grief, and then hope that he will come back to me soon. I have trouble sleeping and I am losing weight because food does not appeal to me at all. (Which is not normal for me!!) But I know that even if he does, things will never be the same because he hurt me so deeply. It will take a long time to repair the damage he did.
I just needed to get this out...I know what I need to do....stay in counseling, try to move on, try to start healing, and not be in contact with him.
Please just say a prayer for me if you are reading this that God will show me what to do and help me heal. I need to be strong.
I know time heals all wounds and I will be ok eventually, but right now it hurts so badly.