I saw a film about 10 years ago, can't for the life of me find it again though :(
It was made in the 1970's or 80's. Its about a gang leader who meets a girl and falls in love so he tries to leave the gang. Then the enemy gang kills his girlfriend, and unlike most other films at this point rather than going on a rampage he has a complete breakdown and spends all his time drinking etc.
I remember it was extremely violent and graphic - the last fight scene was at a train yards from memory. I remember they showed a guys hand getting sliced open pretty bad with a knife.
Its a low - medium budget film as well.