Hello Cherrywaves, Welcome to SR!
I'm really sorry for what brings you here...your story is very familiar to us.
No one here can tell you whether or not to stay with your boyfriend or to leave. That decision is entirely up to you, and I think it will depend on what you are willing to accept as you weigh the pros and cons of this relationship.
I know that my husband and I used to try to have logical conversations with his son about his drinking and drug use -- and the behaviors that came along with it. Sadly, there was simply no reaching him while he is actively using. It's impossible to have a conversation with an active addict.
My stepson, when sober, is a very charming, sweet man who would do anything for anyone. When he is drunk, he is condescending and sarcastic. When he is high on crack, he is beligerent, aggressive, and violent. All three of these people are my stepson. They cannot be separated, and my husband and I had to accept that. The same holds true for all alcoholics and addicts--as long as someone is using or drinking, there is no separating the behaviors.
I hope you will stick around, vent here as often as you need!
Welcome, again.