I (20M) messed up in my relationship with my partner(21-NB) what should I do?

Hi I’m 20 yrs old with my partner who is 21 yrs old, we have been in a relationship for 3 years and it’s been rocky but okay. Until July of last year I been cheating on them with E-girls until March of this year I got caught. Of course I know I’m an asshole this will not change it. For a long time I been nothing but an asshole and an abuser. I neglected my partner when they needed me, I lied about everything(I’m a compulsive liar), and today I said something I regretted so much. When they asked why I cheated on them I said “bc of my porn addiction and my selfishness” but when they asked why I never “finished” in them I said “I think it’s bc I don’t think about them” I know what I said is rly fucked up and I’m fully responsible for everything. Surprisedly they chose to give me one last chance(this was in March sorry everything is all over the place) but today our relationship is nearly hitting its breaking point. I understand that they don’t trust or believe me which is fair. But the thing is I love them so much and I want to makeup for all the things I betrayed and destroyed in our relationship. What do I do, I don’t want our relationship to end(I also understand if this is selfish of me).