My boyfriend said his biggest regret was signing his rights away

I swear every time the weed comes in the truth comes out. My boyfriend told me a long while ago he had a sign who he signed his writes away from. When he was 18 he slept with his boss who was in her late 30's. She had known him since he was 16 and he had no idea she was married and she hid that from everyone. He got her pregnant and her husband decided to stay with her. My bf was living in a tiny apartment at the time and after the baby was born he knew he was gonna be on child support but still got the things he needed from his apartment. The first time he told me this story he said that his bosses husband came by to talk to him and convince him to sign his rights away so he could adopt the child because he can't afford a kid and the kids would see him and his wife as there parents and would live with money and then have to go see him in his small apartment and that my bf would be a stranger. My bf said no at first but thought about it and decided to. I know he still sometimes looks on his former bosses Facebook just to see how he's doing. The child is 10 now. When we first talked about it he seemed fine with his decision but idk if it was the weed but he asked what my biggest regret was and I said not staying and finishing high school and I asked his and he started crying and saying he severely regrets signing his rights away from his son. He told me he wasn't completely honest the first time talking about this and it wasn't just one time of his formers bosses husband asking him to sign his rights away. It was was about a month if both of them harassing and fighting him on it and they didn't want to give him his son on visitations and it was so much and he started believing what they said about him not being able to be a good father. My boyfriend knew that they wanted him out of the picture because that was the only way to save their marriage but he thought his son would be better off in a 2 parent home and in the end it didn't work out because his former boss and her husband divorced several years later anyway. But he has regretted that decision every single day and wish he knew more back when he was so young and actually knew his rights as the child's father. And if he did he might have made a different decision. I didn't understand why all these feelings were coming out now but I found out it's because last month he creeped on his former bosses Facebook just to see how his son was doing and saw she made a post saying CPS "stole" her son and had an illegal warrant to come into her home. So his child is in CPS custody and he seems to blame himself. I want to offer comfort but I'm so bad in these situations. All I could think to do was pat him on the back.