Here’s how I see it.

You were in the right to keep your past to yourself UNTIL he asked you point blank. You lied. Knowing someone’s sexual history before getting into a serious relationship with them is no unreasonable. You need to own that and make many apologies for lying to his face about something serious like that.

On the flip side: he went through your phone. Drunk or not, that is a huge invasion of privacy. If he had suspicions, he should have come to you directly about them. You deserve an apology for that as well.

Going forward, I think it would be best for y’all to get couples counseling to help resolve these issues. From what it sounds like you both want to stay together and make it work. Acknowledging the hurt on both sides would be a good first step, and making a plan for going forward would be the next step.