Tough friendship

Hello,
I've had a friend for almost 10 years now and even we have had our problems in the past but always worked it out. One year ago we started living together but it went horribly wrong. We lived in the apartment her parents but her so I paid her parents rent every month (it was quite expensive). She is very dirty, sloppy, immature and irresponsible so I ended up doing all the cleaning by myself and when I asked her to do some cleaning she always responded with "I will" but then nothing happened. After a year I got so fed up with it that I decided to move back to my parents. I wasn't going to pay that much money every month when I had to come home every day in one giant, dirty mess that I had to clean. I decided I wanted to leave at the end of june but she was on vacation at the time. I decided I didn't want to spoil her vacation so I told her I was leaving when she got back, on the 10th of july. I left a few days later without any hard feelings whatsoever.
In the contract there is a term of notice (1 month). But since we have been good friends for so long time and I practically was a cleaning lady, and only was 10 days too late with telling her I wanted to leave, she wanted me to still pay one month's rent. I decided to pay the half of it and since then we are fighting.
We have a lot of mutual friends and I haven't told them anything about this, because I don't want to be responsible for them thinking negative about her. It's a problem between me and her and it's nobody else's business. Unfortunately, that's not her way of thinking. She told everyone and now almost all of our mutual friends have sided against me (so without them even knowing my side of the story). It was my birthday a few days ago and none of them even congratulated me.
We have a mutual friend named Lucy and her mother is very ill. Lucy has also decided to side against me because of what happened with my friend/roommate. Yesterday Lucy got the news her mother is going to die soon. She made a group-chat on WhatsApp with all of her friends in it to tell this terrible news. Everyone, except me. My best friend told me the news and even though Lucy didn't thought I was important enough to tell this news to, I immediately got in my car, bought flowers and went to her home to comfort her. My ex-roommate was there as well and I acted normal, just said normal hello and goodbyes, for the sake of Lucy who I know is in the mood for our drama. My ex-roommate dissed me and looked at me very angry and said: "I expect you to call me this week". I was kind of flabbergasted, we were al there to comfort out friend who's mother is going to die and she finds it necessary to bring this up. I didn't want to make a big deal out of it so I just responded with 'Okay, I will call you.' It was terrible and I felt like crap but Lucy didn't expect me to come by and she really appreciated it. That's what made it worth it.

There are a lot of things I have to deal with. I always try to do the good thing, when my friends are in need I drop everything and I'm there for them. Always. Even when they treat me like $#%^. What do I have to do with this friend/roommate? Do I have to call her? And what do I have to do with Lucy? She obviously ignored me weeks before this, didn't congratulate me on my birthday and even though I always had been there for her when she was so sad about her mom being so ill, she didn't even bother to tell me her mother is going to die soon. What to do?

Hi flower and welcome
I'm going to move your post to the relationships forum as I think it would be more appropriately placed there.
Take care,
Jan

She is just an angry person who wants to hold a grudge for wtvr reason (some ppl are like that)
If she already talked to all the mutual friends and you want them to know the truth, post is somewhere where they can see it and leave it at that
She is just trying to pour all her negativity on you and she will as long as you allow her