My biological father sent me a Facebook request (part 2)

So I talked to my mom and told her he sent me a Facebook request. I'm 21 and I've never met him. My mom went on to tell me that when she knew him, he was an alcoholic, a womanizer, emotionally troubled, and was accused of sexual harassment by another woman. And one time when they were together she found a bunch of pictures he had taken of naked women without them knowing and she found one of herself when she was showering. She also told me that he wanted my mom to get an abortion when he found out she was pregnant with me and wouldn't hold me or try to get to know me when I was born. He is adopted and his adoption records are sealed, so even if I wanted to contact him to learn more about him to learn more about me (medically, genetically) I can't. I just don't know what to do. Should I accept a Facebook friend request from the man who's never tried to contact me until now? I also have my dad, the one I consider to be my dad because he stepped up and raised me as his own since I was a baby, so I'm not lacking a father figure. I don't want to hurt him by contacting my biological father. What should I do?