Need support please/baby daddy sucks

So I'm new to the group. Had my ds Dec 31 and he's amazing!. Ok so here it goes. My bf is a major dick. He has 3 children before we got together but can't see them do to the fact that his brother adopted them. Yea...his brother has custody of them. So anyways..here's the problem: I feel as though he doesn't love our son as much as the first three he had with his wife. He has even told me so...that he's trying to be a good dad but feels that he'll be taken away as well...but here's the thing..I'm not a drug addict like his first wife and I wish he'd understand that. I feel so alone with this  issue. And he's still married to her after over 2 years of being separated. And he keeps promising he'lI marry me....I feel alone and need help. Very sad. Sorry to be a downer y'all