Hi bloomy,
I'm so sorry that you're going through this.
It's common for alcoholics/addicts to turn everything around, when confronted. That way they don't have to face their own problems, and they can remain in denial. Like when I found bottles, my AH went ballistic on me snooping through his stuff, how he deserved privacy, how very wrong I was. This was early on, and it totally worked, I shut up about his drinking for a while.

You're probably not wrong to suspect their relationship is either inappropriate, now, or heading that way. Adultery begins in the heart. Do you have a pastor that you could confide in? Even if your pastor is also his pastor, he/she would be a safe person to talk to about your feelings and suspicions. As Christians, we're supposed to confront our fellow Christians who are out of line. So, this is definitely one of those instances where having a pastor to talk with and possibly help confront your H with, would be appropriate.

I've not been able to talk with many of my friends about my husband's alcoholism, because we are couple-friends with the husbands/wives. It's hard. We don't want to sound like we're completely maligning our H's, so we just keep quiet. I've been working on developing my friendship circle, though. Making a point to call/email a few friends, get together with them, and be there for them. I know that as my husband's alcoholism gets worse, I will need more emotional support.

The next time you are ready to talk with your husband about this, choose a time when he's sober, and talk with him, honestly, about how you are hurting over this. You may get further by presenting your own hurt, than by telling him how wrong he is.

Alcoholics lie. It's part of the nature of the disease. I've come to the point that I just assume everything my H says is a lie, until it's shown to me otherwise. Where he is/was is a lie, his motives are a lie, what he's doing is a lie, the reasons for everything he does is a lie. Believe your own gut instinct. This past week, I was doubting my instincts, thinking maybe he wasn't drinking, but he was saying nasty things to me, and making me crazy, but I wasn't finding empties in the recycle bin daily, so I thought, maybe he wasn't drinking -- wrong. I found a large water canteen, with a small amount of wine left in it, under his bed, one evening after work. He must be pouring the wine into canteens, at work, to bring home each evening, so he won't have the empties to dispose of at home. (My AH drinks at work, daily now.)

Just trust your instincts on this. And confide in a pastor or elder in your church. Sending you big hugs.