Once an abuser, always?

My boyfriend and I have been together for a year and a half. He's always had a temper. Upon talking to his mom, I found out that his father was abusiveentally and physically to her while my boyfriend was growing up. I've never been scared of him, even when he flies off the handle, I just get annoyed and walk away (we've gone through multiple game controllers because if he loses a game, one usually goes flying to the other side of the room - he's 26.) At Christmas time, he put his hands on me for the first time. Bruises all up my arms... He apologized for it and he would kiss my bruises and tell me how sorry he was and that he never wants to do anything like that ever again... And then he even enrolled himself into anger management classes to learn to control his temper... And things are going good, he hasn't touched me (in a way I didn't want to be) since. But when his temper flares up, I start to get a little worried. I love him, and I'm glad he's working on his anger for me but I'm just nervous that it's going to happen Again... Especially after the history with his father...