Blame or finding wrong in someone’s behavior seems necessary to setting boundaries–is It?

My relationship with my friend / mentor changed drastically. Well after the fact, I found out from what others have told me, she said she felt I competed with her and over time she slowly withdrew from me. I had no idea what was happening then. I did not intend to compete, and adored my mentor and if i was behaving competitively unintentionally, I would have stopped. Before I knew what was going on, or understood why she was distant , she would say that nothing is wrong, or that work was busy, but I felt there was something wrong because she stopped wanting to hang out with me. Her and I, plus two other women had a trip planned. I’ve found out that she went around talking to our mutual friends about how should couldn’t bear the thought of sleeping in a tent with me. She also conveyed to our mutual friends that her and I had “issues” but at that time, I had no idea why any of this was happening. It is like she decided we had “issues” and then proceeded to cause conflict and create distance. Three friends have told me she has said to them respectively, “i don’t want to be on the adventure race with (me)”. “I won’t sleep in tent with (me)” “I don’t enjoy running with (me) because she runs too fast.” She refused to go on the trip we all had planned if I went. She texted me and said we shouldn’t hang out alone or talk alone.” and that she would not go on this trip if I went. she has refused to talk about any of this to me. She just said there is nothing to talk about.

After saying she didn’t want to talk alone, she texted me about work, I told her to please email, not text because I needed that boundary. She texted me “happy birthday”, and again, I said, considering the way things are, I need to not have casual texts and contact, so unless and until we talk about what is going on, I don’t want this contact from you. She then blocked me on all social media, which is fine.

My issue is that I think her behavior is wrong. I can’t help it. How do I stop blaming her? I feel like I asked her several times to tell me what was up, and she just wouldn’t. But, she talked badly about me to others, she told others that I competed with her and that was making her upset.

We have a group of friends who understand what has happened with me and my mentor. I suspect that they will want me to push this under the rug and still hang out with her and them in a group. I feel like to do so will be a breach of a boundary I have set.

My question is I want to set a boundary that I will not hang out with my ex-friend /mentor in groups or at all because I don’t trust her now. I don’t believe she cares for me, or values me, or has the ability or desire to be honest with me. I was deeply hurt when this relationship ended. We have tons of mutual friends though who often hang out. I want to maintain those individual friendships, but I don’t feel like I want to choose to be around my old mentor / friend because of the dishonesty and where things are at. I need to be able to say no confidently when this summer I am asked to “move on” by the mutual friends for the sake of maintaining out group of friends.

C- friendship changed
T- I don’t want friendships that have this amount of dishonestly and lack of communication,
F- safe
A-end that relationship (even in groups), and cultivate new friendship and maintain the other individual friendships one-one without my ex friend being involved. My boundary is there to protect me from dishonesty and a friendship that lacked the level of communication and respect that I want in my friends. and, this boundary will allow me to openly seek people who can and want to fulfill that rule
R- I create close friendships with others who I trust and communicate with about the bad / good.

But, to create the boundary, i feel like I have to make a judgment or blame her about her behavior. DO I? Otherwise, if her behavior wasn’t wrong, I would not need this boundary. Do I need to justify the boundary? How to do have a boundary without justifying it? Or attributing right/ wrong to her behavior that is causing me to want this boundary? I know I am not doing this boundary to punish her, I am doing the boundary to protect myself.