What can I do about my overbearing parents?

Ok so I’m 19 yrs old going on 20 and I have this girlfriend that I love with all of my heart, I mean I think she could really be the one. But no matter what I do my parents want me to not be with her. My dad is extremely controlling and when I dont do exactly what he wants he has a huge fit and starts screaming at me calling me and her all kinds of inappropiate names. My mom just cries and tell me how she’s evil and gets very over dramtic and neither of them will listen to anything I have to say. I made a lot of mistakes over the past year with my school work and other choices I made but none of those things were her fault yet they blame it all on her and they blame every little thing that goes wrong now on here without putting on blame on themselves for putting to much pressure on me or myself for not doing what I had to do. I want to tell them how I feel but whenever I try to tell them they just get all hysterical and won’t listen to the words I say. I dont want to lose this girl again she is so important to me but how do I get my parents to back off, listen to me, and realize I am and adult who is capable of and needs to be left to making my own decisions for myself?