Am i wrong?

My fiances babymom is racist towards me, harasses me, tries to text my fiance sexual things begging him to have sex with her or sneak in her house, and even tried to come to the house to fight me cause he texted her pretending to be me on his phone telling her he couldn’t get his son cause he’s at work. i treated her son as my own but as soon as she found out about me and found out my fiance bought a house she’s been going crazy. so i completely stepped back from helping my fiance take care of his son. me and him were going to the bank and she randomly texted him telling him can he pick up his son early and when we went to go get him. i was uncomfortable being in the car to go and told him that, because she’s always been trying to fight me for absolutely no reason and he got mad at me and said “im going for my son”. when we got there my fiance kindly told her that he will get everything from her car and take it to his car and she didn’t like that so she decided to come to his car to bring her sons toys. she seen me then as soon as he got his son strapped in his seat, she started walking to her car and randomly called him a btch ssa ngga then rushed to her car and started pulling out. he started yelling at her and threw a water bottle at her car. she stopped her car and pulled out her phone and said “give me my son” and she got him. then kept yelling out the n word with the hard er to him. he blocked her ever since that happened cause she also left nasty messages about me and him. but recently she got in contact with him. he got his son this past weekend and now he said that she told him that she may be going to jail because she has to go to court and if he can take custody if she goes. i say anything cause i didn’t want anything to do with that. cause like i said after all the disrespect she’s done, i don’t wanna help out with anything pertaining to her. so now he’s mad at me because i didn’t want to watch his son for him when he only gets him for the weekend. he also claimed that i don’t know what’s good for his son cause i never was a parent whenever i suggest things he should do for him. he keeps threatening to get female babysitters and says he thinks his im jealous of his son which is wild cause i used to watch his son all the time while i was pregnant and while he went out to party and literally bought him mostly everything that’s at the house. so am i wrong for stepping back?