My girlfriend is endlessly loving and supportive. She is never judgemental and always forgives me for any missteps. She is really all I could ask for and I love her so fucking much.

I have been off the rails since last November. I think I'm in a massive depressive spiral that has sent my BPD haywire, but even before that I would episode fairly often. These days I episode near daily. I am extremely awful to her. I always apologise but it's not enough. Despite numerous attempts and motivation to help myself and find coping mechanisms, I'm incapable of changing. I've already 'accepted' but not forgiven my past behaviour too many times to count, trying to use it as motivation for healing...but I fail within a few days every time. The guilt is insurmountable. I can't take it anymore. 

She tells me it's ok and that she forgives me and it's enough for me to simply not give up, but I'm sick of hurting her. I'm sick of watching her take so much on herself when I feel like I'm abusive and our relationship is unhealthy. She deserves so much better. I guess I have 'broken up' with her, because I've decided that isolating myself so I can't hurt her or anyone else again is the right choice. If I'm incapable of helping myself and I'm only going to keep hurting her, this is the morally right choice, isn't it? I don't want her to hurt anymore. 

I wish I could rip the BPD out of me, but I can't. I'm very sick and probably don't have the time left to work through therapy and see any real results. I can't take meds. I can't change the biggest contributers to my depression or mitigate the stressors in my life. I think I'm always going to be like this.

Ironically, this will hurt her more than anything and I hate myself for throwing it back in her face like this. She doesn't deserve any of this either way but it's selfish to keep putting her through it. 

I'm just not sure I'm making the right decision? I'm completely at rock bottom. I don't think I deserve anything, especially her selflessness and understanding. I appreciate everything she's done for me more than anyone could know, but I don't think it's right to keep subjecting her to the nasty shit I say and do and think because I'm so out of control. She says its her decision to make and it's not what she wants, but I feel like she's just blinded right now. I don't know. I can't accept what I am anymore. I'm sick of believing I can get better only to fuck up within hours. I don't have any hope left. I love her so much but I can't stop hurting her.

Am I supposed to learn to accept that she loves me unconditionally? Or do I leave because I know deep down everything I've said and done is unforgivable and she deserves better. I'm really lost.