Is my boyfriend actually depressed?

I have been with my boyfriend for 4 and 1/2 years, we've lived together for 3. When we moved in together, I didn't know that he had suffered from severe depression in the past, so bad that he attempted suicide and had to be committed. Well, that was ten years ago. However, 2 years ago things weren't going so well for him. Right before we met, he had been casually dating a woman who got pregnant on purpose in order to get him to marry her and he now has a child he never wanted. This has been a source of anger for him for 4 years. In addition to that, he wasn't happy with his job and he and I were fighting because we had different views on how people living together should share finances and household responsibilities. To make himself feel better about all this, he began going to online dating sites, meeting women, and having sexual relationships with them. I found out about it a year and a half ago, and threatened to leave. He begged me not to, promised to get help and told me he was doing so. However, last week I found out that he had been having a relationship with another woman that just ended last month when she found out about me, threatened to tell me about them, and he slapped a restraining order on her. Now I've pretty much had it and I'm in the process of moving out, but he and his mother are begging me to go with him to therapy and please try to understand that he truly loves me but his mental illness makes him do these things. I think he seems more like a sex addict than someone suffering from depression but he swears that's not it. What do you think?

I have to say I agree with Karen. Though someone with depression could use sex as an emotional outlet, I would still feel that being he is in a relationship with you, that is still no excuse. But then I'm not very forgiving when it comes to cheating partners either, especially if they're seeking out other partners on the internet, not just the "we were drunk and it just happened" kind of cheating, you know? I would say if you're going to go to any sort of appointment with him it should be one to get tested for STDs, and let him figure out his issues on his own.