My husband doesn't want to end friendship with female friend!!

To start off my husband and I have not been in a great place in a long time. We would argue and then make up consistently for months. Everything was by NO means perfect, but we kept trying at it. One day he said he wanted to sleep with other women hoping it would improve our relationship. There was no way I would agree with his decision or be comfortable with it. After that I felt a little insecure.

So a few months later my husband started acting differently. I knew something was up. He would lie to me. Saying things like "I'm going outside to talk to my mom" or "I'm going outside to get some fresh air." So me being a trusting wife I let it go. But one night my curiosity got the best of me. I went online and looked at the phone bill and I found multiple hour plus long calls from a particular number. I called the number to confirm that it was a woman and I was. That night I confronted him and asked if he was talking to a woman over the past 2 months. He denied it. But eventually said that he was and I would not understand the situation.

This is what he told me. The woman he has been talking to is a coworker of his. Lets call her Jane. Jane is the mistress of another one of his coworkers/friends(Steve). Steve has been in a relationship with Mary for 4 years. During that whole time he was also seeing Jane.

My husband says he was being deceitful and lying because I know Steve and Mary. I met them 2-3 times. But its not like we're friends and we don't run in the same circles. Jane asked him not to tell and he was true to her.

I asked my husband to end his friendship with Jane because I was uncomfortable with the whole situation. He lied to me to protect someone I don't know from a hole in the wall. To be honest I still don't know the womans name. I just don't feel completely comfortable because the whole situation( in my eyes) stems from lies. Don't get me wrong, I don't mind him having female friends but all the secrets surrounding this woman make me feel uncomfortable.

Like I said before our relationship has not been great. So I gave him an ultimatum. To end the relationship with his female friend or end our relationship. He decided he wanted to continue being friends with Jane. So as of now we are no longer together. His reason: Jane has never been able to open up to anyone and she is opening up to me. She is finally starting to trust someone and I don't want to lose my friend. Funny thing about that my husband doesn't have her phone number so she is the only one who can reach out. I thought friendships were supposed to go both ways. But in the end my husband is willing to give up our 11 year relationship for someone he has been talking to for 2 months. The sad thing about it is I told him that I was losing faith/trust in him. But he is willing to remain friends with Jane so she can learn to trust again.