My mum keeps going back to the same guy

My mum keeps going back to the same guy and it's frustrating

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Look, love my mum, but this is one of the only things I can't keep up with. She dated this guy for a bit over a year last year, and ever since she broke up with him, all she does is talk about him. She is currently in a relationship with another guy he is really nice but I know they aren't going to work out because they are both still in love with other people and he is too wrapped up in his life and kids to even spend time with her. Now, back to the problem, the guy she wants to go back to, let's call him Jack. Jack has so many red flags. He always made my mum do everything for him, and he would say stuff like, " Oh, do you want me to help you?" But would make no effort to help at all. My sister and I kept telling my mum about this, but she was too caught up in her own world. After she broke up with him, he basically stalked her and sent her emails and even letters and presents for months. He is also very immature and this really annoys me, he is like a fucking kid (he is 58 btw). Once we were out in a restaurant and he complained about the carbonara because it had an egg yoak on top, which mind you is traditional. And then I was talking about this kid in my class who was racist and kept saying the n word even though he was white, and THIS MAN GOES AND SAYS " Oh? N\*\*\*a? " OUT FUCKING LOUD IN A RESTAURANT, mind you he is white. When I told him to stop, he kept saying it. My mum keeps ignoring all the red flags because he wants to do the things she wants to do... I'm just so done. I hate the guy, and I know my mum can do way better. Also I'm pretty sure he is homophobic and my sister and I are both lesbians so...