I feel so lost, have no one to talk to.

My husband and I have been together 4 1/2 years. 4 years ago when we were still a new couple we both worked as cna at a nursing home. We got a new nurse and I took notice he was always around her. We used the same phone. So one night I went to txt someone and I saw txt between them and turns out they have been flirting and caressing hands telling each other they like each other. So when I confronted him he acted like no big deal. I left him and called her a how. She also has a man and child at that time. Word got out at work, they both denied it and made everyone beleive I was an over controlling crazy girlfriend. And other coworkers then talked about me and made jokes. Would tell new nurses to watch out about me.

Current situation:

We got back together after long talks,

4 years later he has never had a facebook. His brother made him one and so now he has one. I use his phone at home he takes mine to work. So right when his fb was mad I blocked two people that nurse being one. Just didn't want him to see her on there by accident I never thought he would actually look her up but didn't want him curious if he did see her. Couple days ago I noticed he unblocked her. And yesterday I noticed he had been messaging her. Any advice.