Leaving a Relationship for Someone Else (Cont.)

I asked for opinions yesterday. And I've completely decided. I want to leave my current relationship in hopes that a relationship with my best friend is exactly what I want. My only concern, breaking it off with my current boyfriend. I'm convinced he won't take it well, or will try to make his cheating look like it's my fault. Emotionally and verbally, I think he may become abusive. I feel ridiculous asking this, I'm 23 years old and a full time student. I worry about this stuff. I shouldn't have to. Any advice as to how to end this relationship without excessive worry will be much appreciated...