Right folks, need a bit of advice!

Firstly I should mention that she is BiPolar, though medicated since I've known her so it's never really been an issue...

My girlfriend and I have been together (on and off again) for a total of 6 years. I was a young and optimistic 24 year old and even took on the responsibility of being a step father to her 6 year old daughter at the time. The kid is now 13 and we have a beautiful relationship, further complicating the issue.

During the first 2 years, she broke it off with me twice and begged me back. We decided to work it out those two times. Maybe I was an idiot...who knows.

Fast forward another year into the relationship, I took a 6 month secondment in Frankfurt for work. We went long distance and while everything was working for us, I was really struggling out there - being away from her, my friends and my dog. 2 weeks before I was due to return, she broke it off over skype out of the blue.

This truly broke me. I haven't really been the same since. I have built a wall around myself and...shall we say...enjoyed the single life for a while. We would still occasionally hook up when she was in town, but both understood we were just friends with benefits.

This summer (between lockdowns) she came over and once again begged me back. Having had my heart broken by her before, I was extremely wary. Eventually, I told her I would give her 6 months to prove that she really had changed. If I fell back in love with her - great. If not, it would be her who got hurt. Something which she understood and accepted.

When the second lockdown started (we are in the UK) I agreed to stay at hers so that we could support each other through the stress and loneliness of the current situation. Things were ok, but despite her telling me she loved me a lot, I could never quite reciprocate it. Now, I am unsure if this was because I dont feel the same, or if this was simply due to the walls I had built after she broke my heart before. Maybe I just dont trust her anymore? who knows.

Now here is the real kicker:

She has been having some jealousy issues regarding some girls who I was seeing while we were NOT together. Last week, we got drunk together and she asked me to explain why I had slept with a certain girl (not that it was any of her business). While I was trying to explain, she became more and more irate, eventually hitting me in the face and sending my glasses flying across the room and slightly marking my nose from the impact. I immediately left the house and took my dog for a midnight walk just to get away. If there had been a train at that time of night I would have left there and then. I came back to the house (as I had no where else to go - she lives in a different town to me) and she had genuinely forgotten she did it. She only knew SOMETHING bad had happened.

I slept on the sofa and we spoke the next day. I told her I would be leaving to "have some space and time" to decide what to do next. Her disorder is getting out of hand for the first time in our relationship and I'm caught between wanting to help her out of it, and running for the hills. It's just too many obstacles and too much baggage.

So questions: Do you think the relationship is even worth saving? How likely is it she will resort to physical violence again?

Truth be told, I'm already 90% sure that this is the end. Maybe I'm just looking for confirmation from you lovely people....

EDIT: I feel its only fair to mention that when we were good, we were great. I'm just not sure I feel that way anymore.