Male seeking to help female friend

Hello everyone, I have a female friend who tends to find herself dating scumb bags her last few serious realiontships have tended to lean towards the men verbaly abusing her. In her longest realationship that lasted for three years 17-20 yrs of age on her part; the man would throw things punch the walls etc... I'm not sure if he ever hit her,but to this day he still threatens her. I was wondering if there is anything i can do to help her rebuild her self-esteem , help comfort her in re-finding herself, and to help her stay away from abusive men. I don't really understand why she go's back to them maybe because she is used to that or she feels like that's all she is worth, but I feel like i'm in the position to let her know she's worth more than that, what can I do? is hanging out and being nice to her enough? should i just keep my mouth shut and not give that kind of support. Currently she is enjoying being single and just hangin with the boys. Any advice would be wonderful.

thanks, Dave Tweet