Is it controlling so send this to my ex whom I want to be friends with?

My ex and I ended on bad terms, she said from the start she probably wants to be friends in the future. Now we are 3 months into the future and she still dont event want to text og talk. I haven’t been able to think about anything other then the friendship and it’s ruining my life. She has said to me that if I start hanging out with a person we know that we will never be friends and I listent. Now I have the same feelings about someone she can’t do stuff with if we can be friends. She has a ex witch she became friends with asien 3 days after we broke up, and the first time they met after our breakup. Now she slept at his home saying it side by mean anything and that she just did it for practical reason because he held the party and she still wants to be friends and hope it doesn’t effect me anyhow. Then she got mad that I texted that it effected me, like our relationship never ment anything and she just walks back to the ex as soon as we are over. After she then texts me she wants to sleep at his place acorn but he isent the one holding the party which just shows she lied the first time about the practical she actually texted it was only becouse he held it and if the other held it she would sleep at there house. But now that they do she still wants to slip at he’s house. Is it wrong of me to text her I can’t be her friend with her while she sleeps at his house?, I can’t handle getting at a good state with her and then not being able to see her in her eyes when she horse back to her ex. A friendship is just not fitting I think, what should I do?