So we're board members. I take it we can assume that the church is part of a network of other churches, and the pastor has peers and other, more senior, pastors that he is accountable to?
Well, he did the right thing. He confessed his sin, and he resigned his position. He's got a lot on his plate that he needs to work out, and mostly with his wife. Add to that he's now unemployed with not a lot in the way of prospects, as far at church jobs go, for quite a while.
I assume the woman he was running around with has left the church as well? If not, then she needs to be asked to leave. She can just to to another church on the other side of town and carry on like nothing happened. It will fall on other people to clean up the mess. Now, I assume that you, as a group, are on good terms with all the conservative churches in town and not just the ones in the same Denom. I'n not saying that Sally Hotpants is making it her business to put notches in her lipstick case, one for every pastor she drags down. And it's certainly wrong to gossip. But a discrete word to the wise, here and there, can be a prudent thing.
As far as the Board goes, nuts & bolts wise, first the pulpit had to be filled. If you're a large congregation, then you probably have an assistant pastor who can step right up temporarily. If not, maybe one of the board members can, if they feel comfortable doing pulpit ministry. And depending on the requirements of the Denom.
If there's no one in the local congregation, then one of the larger churches in the area should be able to send someone on loan for a few months.
Next, the board puts word out through the network that the church needs a pastor. You can collect resumes, listen to audition tapes (MP3s, more likely). Always remember, it's better to have no one than the wrong one.
As board members, our responsibility is to the local congregation and its long term spiritual health.
As far as the ex-pastor goes, if I were one of the senior pastors in the network then I would tell this guy that myself and a few other senor pastors will meet with him once a month for six months for prayer & accountability before we even begin to talk about any chance of future ministry for him.
Then, it's a lot of questions. Are he and the wife staying together? Separating but not divorcing? Are they divorcing?
IMO, and I'm probably in the tiniest minority here, a divorce won't necessarily automatically disqualify him from any future ministry.
Depending on how things do with his wife, I could see him being reassigned to another small church in another state. Or a support role at a larger church in another state.
But if he divorces his wife and takes up with the woman he was running around with, or if he refuses to submit to authority & the restoration process by sitting on the shelf for six months, then I'd recommend his ordination be pulled, and he be barred from ministry within the denom.