He cheated with my sister 😥😥

So me and my fiance dated for 7month he proposed to me twice yes, this man used to say mean words to Me , Hr could talk so loud for hours, he will never let me say a word in the process ,He could accuse me of things that I never do But I was quiet all the time . Now am black and he was white , it was my first time dating a white man So I thought he will change with time but No he didn't change , we blocked each , I felt like we can sort the issue out as mature people I mean he was 25yrs older than me so I respected him , I gave my sister his number to try and talk to him ,she talked to him but after 2weeks the two were dating , this shocked me because he had proposed to me 2weeks before the breakup ? Mind you he had never met my sister physically but just on phone, lucky enough I had never slept with him at all because I was waiting for our wedding before giving him the cookie ,SO after about a month of dating my sister he wants to come back to me . AM STILL HEALING,