I don't have any insight into her behaviour. It is hard to know why anyone chooses to behave the way they do, even people closest to us.

What I do note is her pattern of behaviour towards you - how she disappears on you and pops back into your life on her terms or when she chooses. She is simply not there for you.

What I also note is how you talk about yourself - i.e. how you are "garbage" and "deserve all the embarrassing reasons women have broken up with me". I am not saying it is not justified as I don't know what you did (and I am not asking) but I would work on that and grow as an individual or become a better person, so you can seek relationships with mutual care and respect.

Going into relationships with the expectation that it is okay to be used or mistreated because we 'deserve' it feels painful more than anything else.