My husband had an affair at work

If me and my husband aren’t having sex anymore does that make it okay for him

To go and have sex with someone from his job?
Long story short I’ve been dealing with depression which is why I no longer feel the need to be intimate, sex is the last thing on my mind anymore because I’m grieving I’ve lost people in my life that were very important to me. And to make it worse he didn’t confess to me himself, the girl he slept with told me herself and when I confronted him about it he denied it. The only way I got the truth from him was to make a deal that if he just told me the truth we would stay together. And he admitted that yes he did have sex with her at their place of work. My heart is shattered and I don’t know what to do. I could really use some helpful advice.