I need advice. My (52f) and my husband (59m) of 18 years started our enm journey about 4 months ago. We met a unicorn, (not seeking one) and she and my husband went on a date and became close. She spent the weekend and the three of us had an amazing time. It became apparent that she and my husband's dynamic was the one that would be getting the most attention. I thought I would be OK with it. I talked to them to let them know I had a date and thought my husband would benefit from having someone there with him while I was gone. It was my first ever date with a girl. I was so excited and had planned to stay out until 11pm. The date ended an hour and a half after it started. We started in a hotel room and had a great time and then decided to go grab a bite to eat and hang out. I had let her know, that I couldn't just have sex and leave prior to our date. Well, the restaurant was closed and she decided to go home. No offer to go find somewhere else or anything. I had a pretty big drop emotionally and found a place to sit and eat alone. The problem was that I now felt that I needed to honor their time and didn't feel comfortable coming home 4 hours early. I was upset though. I texted and let him know what had happened. He asked if I was OK. I said no, but needed to gather myself before i drove home. I sat there for 2 hours on my own. I got home and he came up to check on me. I didn't really understand how I was feeling and I said I was fine to go back down to her. His office/studio is right below our bed. Hearing them have fun and laugh just sent me into a crying spiral. When she left and he came to bed around 230am, he was so upset that I was hurting and he felt bad. I really struggled with them having sex below me. I let them know.
The unicorn was concerned that I just couldn't handle poly. The three of us had dinner at the house together 2 nights later and talked about it all. I thought we were in a better place. We talked about our rules/boundaries. 1. No overnights away from the house yet. 2. No unprotected sex. I knew they had feelings for eachother and I was starting to feel compersion.

I invited her over for dinner a few nights later. The three ofnus talked, I told them I thought I was in a good spot. We had a lovely dinner. I went to bed. They went downstairs. They had a great night and I was super solid in the morning. I thought that it was a good thing. We could have each other's backs, we could have three-play once in a while...it was good.

Later that night my husband told me that they had unprotected sex. He said he got caught up in the moment and when they realized, they decided to continue. I was devastated. Neither of them saw it as something bad or wrong. Neither of them seemed to understand why I was angry for a "mistake" .

My hurt came from the fact that unprotected sex was not discussed with me. I asked if she has unprotected sex with other people. She said that is her private business and that she treats all her partners the same...she shares her test results. I had sex with my husband unprotected that same morning before he told me. I had no idea about what had happened with them. I feel like I was treated unethically. I felt betrayed and violated. My husband tried to convince me that it was all his responsibility 100% . Hell no. It is 50/50 there. She said continue. She is an experienced unicorn, or so she claims. They should have stopped.

I got tested, he got tested. Thank goodness all is good. I told her how I was just as angry with her behavior as I was with his. I told her I no longer trusted her and distanced myself. We haven't talked. My husband and I are shaky. I love him dearly but ai feel so betrayed and mistreated.

Am I wrong? Was it just a mistake? If the roles were reversed, I don't think I would have chosen to behave the same way. He still wants to have contact with her. That is so difficult for me to wrap my head around. I do not welcome her back, but I also believe he should have the freedom to see/love as he sees fit. I also think I do too and that would mean that I could no longer in good conscious have unprotected sex with my husband because I don't trust her or him anymore.

TL;DR....my husband had unprotected sex with someone and claims mistake. However consetually decided to keep going. They both knew it was non-negotiable- we talked about it together. Am I in the wrong for feeling betrayed by them both.