Complicated 4 yr relationship / help please

I am 22 and have been involved with a girl not much older for almost 4 years. She has OCD, anxiety issues and mild cerebral palsy. I asked her out and we began dating. At the moment I was working a job at a bagel store which I did not enjoy and besides being insecure/low confidence and quick to get angry I am without learning/physical/emotional disability... We became very close very fast and began seeing each other as much as possible, constantly messaging/calling and physically involved--her parents (Mom/Stepfather) were accepting of me at first and after only dating for 5 months she moved into home with my Mom/two-sisters and 2 dogs. Most people can see that this was going too fast: We both work(ed) and came home to each other, but through confrontations about her OCD/anxiety and my own real faults/problems we began arguing/mistreating each other and I made the life mistake of letting myself call names and even shove her. We argued about me playing video games, or sex... Maybe work, friends or family. But sometimes I felt like I had no space and that the moving in was a mistake. We always went back to each others arms and made up, but eventually when my younger, stupider self broke her new smartphone she finally let loose with her parents and they jumped into protection mode; her stepfather even choking me in front of my work place in a heated discussion. I had invited a girl into my home (surrounding by my whole family) and let it tick me off and made mistakes. They moved her back in and her family, friends and co-workers were all warned that I am not to speak/see her. But through facebook/pinger/AIM/steam/texting we keep in touch, and sneak around. The parents being financially okay moved her into an apartment (with her brother temporarily) and help her live there on her own; I got a new job which I truly enjoy and went to a therapist/grew-up/stopped the bad habits that drove me mad. I assisted her to work (she rides a bike), took her to eat, snuggled and watched movies, showered with her, slept next to her, took care of her dog with her/cooked dinner for her. Literally living with her several days a week. This was maintained for 4 years in secret. Besides occasional arguments I changed immensely. Her parents rarely going to her place/picking her up/wanting to see her, often going on trips/cruises without her and overall letting her take care of herself (or so they thought)... I often talk to her about coming out and telling her family and dealing with it. She holds onto me and claims her love every time but says she is not ready to tell her parents about us. Her brother is now moving back in with her in the apartment (because of his own problems) and she is overwhelmed with fear to explain/support our relationship, but keeps dragging me along. I have never tried letting her down or talked to another girl: But even though I have changed/went to therapy and been with her for years I feel like I am losing her to my stupid mistakes/dark past. I know I have a lot of options, and a lot of normal people would suggest drop it, but I am frustrated by simply marking it as a mistake and throwing the relationship away. I love this girl. She loves me. Every flaw included.

GONHXH stop beating yourself up. You were young and naive and you made mistakes but more importantly, you learnt from your mistakes, you had therapy and changed yourself. Be proud of who you are today. As parents of your gf you must understand that they will not be so warming towards you. Their daughter also has mild mental/physical issues will make them even more protective over her. Wouldnt you do the same if this was your daughter? My opinion would be to win over your girfriends parents love. Show them how much you love and care for their daughter. Win their trust over. Their daughter clearly loves you..Give it time, patience and tactics..Im sure the parents will too.