I need advice. Please. I'm losing myself.

I reconnected in December with an old friend and we started dating and things were perfect. No fights, Arguments, etc we both have kids and as a unit together things just fit perfectly. Interests the same, sex life great, home life great when together. She basically picked me up at the lowest point of my life and every day since was like a fairy tale. I have never been more motivated to be who I feel I actually am before.

Within the last 2 weeks we went from waking up side by side in love to her almost completely cutting me out of her life. This happened overnight. She just vanished but kept minimal contact through text. She said she loves me and this is temporary she just needs to work out some things for herself because she doesn't know why but even when things are perfect she has a desire to just jump from person to person.

I want to be respectful. I want to trust her but now I'm finding out in her previous marriage she cheated... All the time. After her marriage for a year before me she was doing all kinds of insane sexual stuff with random partners and then came me. 

She didn't cheat while we were together, she only wanted to be with me and made a point where any time I was free she was already at my house waiting for me after work, etc and I loved that. It was easy, we were great. Her therapist has talked to her about possibly having BPD and my own has said I may have BPD but for sure I do I definitely suffer from severe depression and relationship PTSD.

The only contact I seem to get from her anymore is when I don't message her for a day and then she can't seem to talk to me enough. I had begged her to just talk to me since I hadn't seen or talked to her about what happened in 2 weeks since the split because she would ignore my questions. And when she finally did she came over, we talked for hours and then she jumped on me and we had sex... And my fucking mind told me "ok maybe things are going to be better". But they weren't. They went right back to no meaningful conversation and me left here wondering what I did wrong. 

Even with her past and current issues I don't and can't give up on her or let her go. I've lost motivation to eat, get out of bed, work, be a human being. My normal "jump to the next person" thing didn't kick in and I can't get her out of my head. 

I don't know what to do. I may understand jumping from person to person if the relationship ended badly because of something that went wrong... But this time nothing did and I can't let her go and I want to fucking fight whatever she's dealing with with her because she says she loves me, this is temporary but she doesn't want to hurt me or commit to anyone.

Now that I type this out I feel pathetic but I'm lost. My motivation to exist is not here because the spark she brought to my life left full force when she did. 

I don't even know what advice in asking for. I just don't know what I'm to do to get past this because my brain and heart say hang on but the signs all point to she's being kind telling me she cares and may actually not. Or stopped suddenly?

I can't seem to cope with the fact that everything was perfect and then suddenly it was over. I believe that she split on me but I don't know if that's means to just suck it up and move on, wait and see if her mind changes down the road, I don't know. 

If I message her she will ignore me for a day or more. If I ignore her she messages me. Some days she wants to talk all day and others she says "I want to talk for now" then will drop off the earth mid conversation.

I mean yesterday she messaged me after nothing for 2 days just to tell me she had a migraine... then ignored me the rest of the night. 

I want to be supportive, I want to be there through the good and bad but I also don't want to be a last resort just hanging by a thread until she randomly comes around again. But if this were some normal relationship where BPD wasn't a factor I'd have just bolted.... But I don't want to and I can't seem to get through to her to communicate with me as to what she needs.... 

I can't get out of bed, almost every second of the day she's stuck on my mind trying to rationalize things, and I need something to cope with this because I don't go back to therapy for 3 weeks and my life is falling apart worse by the day

Please