Am I crazy or nahh?

This girl (I’ve been in love with for like ever) and I have been on and off for nearly 7 years. Both of us are stupid apparently because we keep going back but she is the only person I’ve every truly loved. The last time she and I ended things badly she got with another girl for a while and they are now over and have been for a while now and she was finally ready for a relationship and She came to me and asked if we could just at least be friends because she needed me in her life even if Friendship was all she could get. So of course I said yes but there was going to be some stipulations due to her past actions (won’t go into detail of our past) but she was totally fine with it. She currently lives with her sister and her family but her ex is currently staying there too. And we’ve been talking about getting back together. She is 100% done with her and I believe her but am I wrong that it bothers me that her and her ex live in the same house and go everywhere together? I guess it’s like she’s become part of the family but I just don’t get why she can’t tell her to get her shit together and find somewhere for herself to live. 🤷🏻‍♀️ maybe I’m cold hearted.