Kudos for wanting to preserve your marriage, but do realize your husband’s adultery violates your marriage covenant and grants you every right to a divorce. Laying down your rights is often part of the christian walk, but if you want to save your husband from himself, make wise use of this right.
First, cultivate a support network–a Christian counselor, pastor, a spiritually mature friend in the Lord who’s been there, done that–and prepare yourself to be willing and able to leave him if he refuses to shape up (hang with me here.) Then quietly, but firmly ask him if he wants to stay married to you and politely let him know (no demands) what’s going to need to happen to save this marriage. Namely, he’s going to need to take his vows seriously, and get into marriage counseling with you.
If he refuses, pack your bags (plus those of any children) and leave, but be willing (and let him know this) to take him back when he’s ready to get serious. If he says yes with his mouth but no with his heart, give him one strike, then start packing.
The follow-through is vital here. Guys like this, only when they know there will be a serious consequence to their behavior will it end. Depending on the guy, it may take a while for “she means business” to sink in. But hang in there and don’t move back in until after he’s started marriage counseling and shown he’s going to start respecting his marriage vows.
Biblically, this tact is fine for other bad behaviors not specifically covered by scripture (a severe drinking problem, physical abuse) the only difference there is the bible teaches when separating for any other reason besides adultery, you’re to remain single or be reunited to your husband. As that’s the whole goal here, it’s important to realize if this stand off ends in divorce, you’re not the one ending the marriage. He’s already done that. This is vital church discipline the only way he’s going to get it most likely. It’s one thing to do something like this over selfish reasons, but quite another if your motivation is saving your marriage and his soul.
But I’d seek that support network first and get a second, third, and perhaps a fourth and fifth opinion as well–as many as you can get basically. It’s important to get as much input on such a huge step as possible. Plus I want you to have people at your back that can give you a real hug and keep you grounded if he’s the type to play mind games.
Oh, and I’ve left out the most important part–through all of this, stay on your knees carrying your marriage and your husband’s soul to God’s throne. That’s the most powerful weapon you have besides the scriptures. Pray for his soul and the restoration of your marriage, and in doing so know the truth no matter what lies your husband and the enemy try to tell. You’re thick in the heat of spiritual warfare. May God and His Church be with you.
Hang onto that love for your man, sister. It’s the mark of a true woman of God. But it’s also Christ like to practice the “tough love” I’ve recommended, I believe. There is nothing loving about continuing to allow him to walk all over you, dear heart. So stand firm, but also show the respect he needs but doesn’t deserve, and be prepared, once he’s been restored, to also restore him to his proper place as the head of the home, showing him honor and respect as if this never happened. Oh, he’ll need held accountable indefinitely, but it’s best to find him a male accountability partner for that. Definitely ask God to help you in this area. It’s a tough line to walk.
The counseling is pretty much a must. Unless he’s a complete you-know-what, adultery usually springs out of martial difficulties of a two-way street nature. The men who do this because of problems in paradise are wrong, under no circumstances is adultery ever justifiable. But it does mean the underlying issues will need addressed.
If you identify any “beams in your own eye” as Jesus put it, get those out on the table, apologize to him if appropriate (preferably before you confront him about his own offense), and take appropriate steps to get rid of them. That’ll strengthen your position spiritually in this war.
Fair? Heck no. But is fair so much important as what works? The way most men are wired, changing our behavior often times will lead to a change of theirs. But that’s just something to pray about; I don’t know all the factors in your situation.