Honestly, I find it too difficult to hate on ex's or on new partners or the like. I don't have the energy for the hate. As for the ones who were involved before the previous relationship was over; I can definitely say it SUCKS, and I have been there... but the blame really does mostly lie on the person who cheated on you, not on the other party. She has no ties to you and no loyalties to you. (Maybe that is just my opinion...)
However, I DO have a nice story about the whole topic. A friend of mine (who is amazing by the way) started dating a man she was in high school with. They hadn't seen each other in 15 years when they met up again. He had previously been married and had an 8 year old daughter with his ex wife. He and his ex wife were very amicable, and so when my friend came along, she was amicable with the ex wife as well. The ex wife and her new husband and my friend and her new husband all started going for dinner with the little girl, and the ex and her husband ended up having 2 more kids together. My friend can't have children, but they get the 8 year old daughter (who is now about 12-13 I believe) 50% of the time, and the rest of the time they can see her whenever they want. They also have the ex and her husband over for dinner, and all three kids come. The son of the ex and her new husband LOVES my friend and just snuggles into her all the time. They are ALL friends and the kids do not suffer AT ALL through all of it. It is so nice and so mature to see!! It is so lovely. The whole lot of them have been by my fire station to visit as the ex's son LOVES firemen
I feel privileged to know people like that. They are wonderful, all of them.