Desperately trying to make a relationship work with someone you know isn’t good for you

Has anyone done this and know why they did in hindsight? I (27M) recently broke up with my gf (30F) and we still live together until spring. I thought i’d be more relieved but it’s almost like i’m expected to just change my mind and get back with her.

We’ve been together almost 6 years, and I feel like I knew for awhile that this won’t work and I should just drop it. I even moved away to a new city and let her back in thinking it would be different, healthier because we got our shit together.

Hint: I did and she didn’t, so now i’m almost a sugar daddy and that basically killed the whole thing. I suspect she has NPD, BPD, or is quietly autistic. Her actions just don’t make sense or line up with what she says. Yet, if i call her out on it, it’s like she’s aware that she did something wrong but she doesn’t know why she did it.

Now I look back at all the ways I let myself be manipulated, all the times I should’ve just used the umpteenth out, unaware of people pleasing yet aware that this situation is burning me out and putting me against myself.

I don’t want to say I used her because I really don’t stand to gain anything from her, but I thought she was someone that help me have a stable life. Yet, all my problems emotionally, mentally, and financially are partially due to the dysfunction and lies I let in my life. I’m lost and feel like I discarded someone that I probably never wanted in the first place but took 6yrs to do it, and now I feel everything. Did I pity her and want to figure her out? I feel like we’re both victims but the blood is on my hands because all i had to do was remove myself.

I wanted to be there for her and she helped me, but i feel like we’re both going to be traumatized by this.