I'll try to make this short but a little bit of back story is needed.

My (35F) husband (43M) have been together for 8 years and open for three of those years.

We have always been very communicative and have a lot of trust with each other. We opened up and he pursued a former co worker he was good friends with and they've been together most of three years we've been open.

Everything was going great. Couldn't have asked for a better partner and relationship.

Come to find out, (I was looking through his phone for pictures... yes he was aware..., when a "happy 4 years!" Message popped up on his phone) him and his long time girlfriend were having an affair a whole year before we opened. He had multiple times he could have told me.

He also wasn't the one who brought up the open relationship AND he took a long while to process. While processing we talked about everything he had questions about. He ever "confided" in me about wanting to try and with this former co worker. When he "talked" to her about it, apparently she was reluctant to be apart of the dynamic.

The hesitant and conversation he told me about was completely made up.

I feel so betrayed and my trust is completely shattered. It's been 4 weeks and the hurt doesn't seem to be wavering.

I love him and want to work it out but I don't think I can trust the two of them together to not lie to me more.

He offered to cut things off with her but ended up talking to her a couple days later and I suspect they are still talking even after him being insistent that they aren't.

I just don't know how to move forward or if this might be a lost cause.

Please ask any questions for clarification if needed. I really want to get through this, whatever that may be. Any help is appreciated.

PS: I have this posted in a couple different places to get more eyes on it for advice.

Small Update: this past week we were taking space and not talking to each other to just have a mental break from it all. Long story short, he does not want her out of his life and so I will be stepping back from the relationship. We are intermingled financially and with our teens so until that get resolved, we will figure out how to live together. This hurts more than when I first found out honestly.