My friend shouldn't get married.

My friend is planning a wedding for November. She just lost her 21 year old son a couple of months ago. She had asked me to be a bridesmaid, and, I initially said yes. I changed my mind and told her that I was done with the wedding nonsense when I drove her to pick up her deceased son's vehicle.Her fiance left it at a body shop to pick up his vehicle and told her to figure out how to get it. He told her he was going to work and she saw on facebook that he was at a bar. I found out that the day of her sons funeral he accused her of cheating on him with her son's friends and made a scene. He has lied to her about a lot in the course of their relationship and she seems to forget about it. She found out from his family that he did have a son in Florida that he didn't tell her about and lied when she asked him. He also told her that he thought he was divorced but didn't know that he wasn't divorced even though he never when to a court date for it or got a decree of divorce. He is still legally married to someone else and she is supposed to be signing divorce papers that he sent her. Their relationship seems pretty toxic to me and cycles when he feels insecure. She texted me the other night asking when I was planning on telling her that I didn't want any part of her wedding. I already did when we got her sons vehicle. She is acting like it is a surprise. I wish she would wait and work out their issues first. She basically told me to have a nice life. Don't know what to do. Am upset