To top off The Totem Pole

My ex(yes ranting again) was kissed recently by her other ex which really screwed with her mind. This guy twisted her emotions soo much she was willing to marry this asshole(pardon) in a heartbeat....Now she's all odd and wondering about possibilities...and she HAS a b/f...she says she didn't kiss back and just went home...but...I know her a bit...she definetly is thinking of the event...Anyways, I told her to stay away, not only for her sake, but for everyone elses sake...
This is a guy that if I wanted to, I could have 4 or guys beat down into oblivion, sent into a hospital...Not just b/c of what he did to her, but what he DOES to Women in general...I hate scum like him...I pretend to be his friend...I hate being the good guy....*deep breath* but like I'm saying...not really proving online, but I'm doing in real life...My EX is out of my life...I could care less emotionally about her, but I'm still a friend, or aquantance(?) and that will not change...I don't like seeing friends get hurt. Period. I just don't know what to do... leave the situation alone, what? I'm thinking of just talking to her about the guy. Telling her to just forget about him...just leave him as far away as possible out of her life... he'll only make things worse...well, thats my rant...any advice on the situation?