I think I messed up. I cheated on my boyfriend just to experience it. What do you think I should do?
Are you serious? Why would you cheat on your boyfriend?
Firstly, I've never cheated on him before. It's only the second time I did this to someone who I trust...My mind can't help it.
It is bad to cheat on a partner.  Trust is very important in a relationship.
He's probably with other girls too.
You can't make that assumption because it sounds like an excuse to justify your wrongdoing. It's too late now, so your best bet is to just be honest and tell him the truth and promise you would never cheat on him. You have to work hard to earn back the trust in the relationship.