Please help me!

A guy Ive had a crush on for 2 years finaly notices me but its the worst point in his life. He likes me a lot but He is too scare to date because he's been cheated on so many times! i woild never do that to him though... We are super close, talk every day, and hang out a lot! Until things strted getting romantic and then sexual which was my idea... Now im so deep into this I have no clue what to do but its clearly a "friends with benefits" situation. I have no clue where to go from here cuz I like him more than that. How can I make him realize I wont cheat on him?