Struggling with a Breakup and a Rebound

i feel sooo stupid, i recently got broken up with by my girlfriend of a year and i decided to go on a rebound within the same week. (A is ex, B is new girl for simplicity) A wants to keep talking to me however i cant talk to her without feeling immense dread, i of course want to still have her in my life but she has broke up with me before and i can’t help but feel like she leads me on everytime. we flirt, we get back together, she leaves, it’s a cycle and she knows i’d always go back to her and it hurts. (i should probably mention i also have bpd and she was my favourite person for half of our relationship) i feel like i cant cut her off though, i want her to still be there but i don’t want to feel this way about her anymore. she’s a good person but i need to move on. i immediately went for a rebound, went on a dating app, met this new girl (B) super super into her! she’s super into me too, great right? i genuinely do like her and although it’s been barely any time at all since my breakup i think that i could actually like B. but i just have this weight on my shoulders on what to do about A, should i keep her in my life? was the rebound a bad idea? should i go back to A? should i cut her off? i have no idea what to do. i’ve told B i got broken up with very recently so she’s fully aware, but i still feel like it’s a bit unfair on my part.