Are you a horrible person? No, you're not horrible. You just had a bad day and made a mistake. At least you admitted it to your boyfriend and you are wanting to fix the situation. There are millions of people who cheat, lie, keep it a secret and never want to fix the situation. You feel remorse and regret and taking responsibility of your actions is the first step to recovery and forgiveness. I think it would benefit you to talk to a therapist because whatever is bothering you about the past does not seem like it has been dealt with. Yes, trust has to be earned back but look at it this way, he decided to stay with you even through your transgressions instead of leaving. Just in that decision he's telling you he loves you enough to rise through the hard times.