Dating a legally married man

I've been seeing guys for a few months. He is legally married but separated from his ex wife. She doesn't even live in the state. He has full custody of their sons because she filed for abandonment after she left the boys on his door step and left the state. He said his reasoning he didn't is because he had more important things on his mind. His oldest son (14) was hurting himself and had to go impatient because he was talking suicide and his kids were just going through it. Because of insurance issues he was having to pay out of pocket for his kids impatient stay so he didn't have the money to even file for divorce. He also didn't know where his ex was to get her served. Now that things are settled he's planning to file next week. I haven't introduced him to my family yet. Do I wait until the divorce is finalized or just when he files?