Hi there papayagirl,
I join
mutt in welcoming you to the boards. A warm welcome and
I'm sorry about your situation, it must be really confusing for you, especially the kind of mixed signals this person has been sending you. May i just clarify if he has officially been diagnosed clinically by a professional?
A few days later we met up to fix my car, got dinner, and went to watch TV where he completely initiated kissing and sex with me, even after stopping a few times going "We shouldn't". I left afterwards and a few hours he called me and told me he broke up with her. For the next few weeks, he was messaging me every day and seeing me about once a week where we would cuddle and sleep together and all of that. He would call me to vent, call me in an emergency (I picked him up when he hurt his toe hiking and couldn't walk).
This sends me some red

actually, it does seem like this person is using you for "supply" for his emotional needs. It is so heart breaking that while you've been kind toward him and giving him all this attention and care, he suddenly seemed to have flipped a switch later on.
He started pulling away about a week ago, not really talking to me and saying he was "busy" on the days I asked to hang out and I realized I couldn't be just friends so I said something. He replied with "I can't give you more than friends. I'm sorry. I was going to tell you I needed us to be strictly friends and nothing more"
I tried to call him and talk about it, and he ignored me.
He seems to have a "lack of commitment" and cannot stand to "be alone" if it is true that he went back to other person.
I'm sorry that he is just ignoring you like this, this must hurt especially after all the love, care and attention you've given to him.
Papayagirl, i'm really sorry for what has happened. Clearly, this person you are with has issues, it will not be for your benefit further a relationship with a person who cannot commit, but seems to be displaying "boundary" issues too.
I feel like I wasn't good enough, and used. I don't understand how this happened. Do they always line up women like this? I need someone to tell me he's going to do the same thing to whoever he's with, because the thought of him being happily ever after with her makes me want to cry.
Papayagirl, most of us asked tihs question. Why did he/she leave? was it my fault or was i not good enough? But right now your heart strings are pulled and somewhere in you, the hopes and dreams of being together with someone you've been in love ... or madly in love with has crumbled. I say this with gentleness, that while it is difficult, i guess you'd know that this isn't healthy, would you ask yourself if it be okay to go on like this? Not knowing what he would do next? The issues you see with him probably didnt just manifest over the course of your relationship.
It has probably been for him this way for a very long time. You didn't cause it, not can you fix it, and mostly unfortunately you won't be able to change it. This is the detaching board so, how can we help, Payayagirl? Its not so much about you, as it is about him. I do certainly echo mutt that this new lass he is seeing, is certainly no better than you.
Takeheart dear Payayagirl,
Spero