How can I control my feelings as I try to help my best friend/ boyfriend?

It sounds like he has a sexual addiction and you can send him encouraging words and bible verses, but that may not be enough for him to change. He needs to go to sexual addicts anonymous. Look it up on google and get help to break this cycle once and for all. I think once he does that and frees himself, then you can have a true relationship together and get married hopefully. Good luck.