Close call

So I’ve been dating this man for almost two years. I love him so much and lately it’s been hard. We started dating at 18 and now we’re turning 20, this means our relationship started in high school and it was very immature. Now we’re in college and trying to become mature but it hasn’t been easy to get over old tendencies. I’m doing my best but a few weeks ago we had a serious conversation thinking maybe we weren’t right for each other right now. College is such a time for independent growth and we were scared to lose that if we stay together all of college. There’s also always the fear we will not last (even though we believe we will) and these prime years will be wasted. All of this aside though we decided we love each other too much and see a future together and want to stay together.

A week after our talk he got blackout drunk and almost cheated on me. The girl is someone he thought he could trust and she offered to walk him home and took advantage of the situation. I have many witnesses giving me this information so I have no question of the integrity of the info. He was not in control of the situation but I still feel I have to blame him. The girl went home with him but before they did anything other than makeout he stopped the situation. I was told by him that he couldn’t get hard (because of the alcohol) and it caught him off guard and took him out of his blackout state. He then asked the girl to leave. When he told me about the situation it seemed clear to me he was taken advantage of, and if the roles were reversed I, as a girl, wouldn’t have been at fault. He can’t let the guilt go. It’s been eating at him so badly he’s not even himself anymore. He’s like a shell of who he used to be and it’s so hard to witness. He’s been getting blackout every night since and won’t accept getting back together. He says he respects me too much, and although I understand where he’s coming from, I believe this is something we can get past. I’m honestly just looking for someone to be straight up with me. Even now this man is treating me like a princess, but I’m scared to do the work of getting past this and one day regret it. Should I just let go since we already had doubts? I truly see myself marrying him and I don’t want to let go, but I know sometimes things don’t go the way you want and I have no one to be direct with me. Thank you to anyone who read all of that and thanks for any insight.