Cheating problem.

Okay so I know I'm going to get a lot of hate for this but I honestly need advice. So when I was young, about 15, my partner and I broke up because I cheated on him when I was drunk. Obviously being drunk isn't an excuse but the event still majorly effected the both of us. Fast forward a fair few years and now I'm with my current partner and I just don't want it to happen again. I love him with all my heart. I honestly see myself marrying this man and growing a family together. So I clearly don't want to ruin this. It might be a long shot but please I need any help or advice anyone can give. Please.