I made a really immature decision

Well, you're 22. He's 45. Now 90% of Reddit will tell you he's a creep, but in this corner we're going to be a bit less quick to judge. With such an age difference, you can't have a relation as equals. Guess what? A D/s relation is intentionally, consensually, not a relation between equals.

The age difference greatly increases the responsibilities for the Dom. Yes, it's still your fault for not telling him. You did break his trust. But you understand this. It's now his turn, both as the Dom and the more mature partner. He's showing good signs - he openly acknowledges the risk that he could abuse this, and acknowledges that he shouldn't.

You're still wondering what to do, though. The simple answer is very short. Be a sub. Leave what has happened to your Dom, and let him play his role. When he says to let it go, do not question this. This order is for your mental health, obey it.