Need some feedback

My friend (poor thing) is dating the worst of worst guy... He has health issues, he doesn't like white people, and basically he is a bitch.... To me that is.... Okay now... My friend has mixed kids... Half white. He is not mean to the kids but he seems jealous of her. He tells her she shouldn't do everything for them. And tells them things that are just negative. Well they went to a wedding and one of her kids was a groomsmen (which is kind of a big deal) the boyfriend finds everything wrong with the wedding. 1. The couple was white. 2. He didn't like the fact that people kept complimenting her about how awesome her kids were. It bothered him bad. 3. The usher took her hand and led them to their sits he got mad and said that's my job I'm your man. He was just a total b hole...I asked her are you cool with that? Do you think that's okay for him to be like that? I said girl something is wrong with you... I don't know if your feeling low, and desperate but you need to get it together. They dude is no good.. She started taking up for him. So I shutup. My question is how do tell someone that you don't want to hear that bs with out then getting offended