Why can't I get control?

I know not doing anything is not good at all. But that is what I have been doing. My relationship with my boyfriend is falling apart because I can't control my son's behavior and when he does something wrong, I don't punish him and therefore he does it again and again. I am spinning out of control and don't know how to regain my strength to fight this battle. I love my boyfriend and I have hurt him and he resents me for all the things my son has done. I want to rebuild and strengthen but I don't know where to start. My son has to change his ways or things will always be the same. But what will it take for him to change? What will it take for me to change him? Where do I start? I need to break this cycle before I break down. It has taken a toll on me emotionally and I am feeling so alone.