If you're still reading, @hiimtheproblem , think about doing the following:
If you're sleeping with your husband, stop.
Also stop sleeping with the OM for now.
Spend the next few days reflecting, and also gathering your business together wrt you having to suddenly leave the house in an emotional state. Passport, birth cert. bank bits, phone charger, whatever. Think of a place you could go. Friend, family, hotel ect.
Chose a time and talk to your husband and tell him the marriage is in trouble. Be as honest as you can ... If he wants you to move out there and then you'll have to agree. Prepare for him to be really angry and upset. You'll have to accept that with grace.
Don't move straight to some temporary bolt hole with the OM. You and your husband need to make decisions on your marriage.
I would tell OM what you're planning to do, because his reaction will tell you A LOT.
I would not tell the kids details obvs. Tell them something appropriate.
Although your world will fall down around your ears you will feel relief at being honest and doing the right thing. Plus you will probably find your feelings towards OM will change from being a fantasy thing to something based in reality. One way or the other.
The thing is you can't carry on as you are without destroying your own sense of self worth and going further and further down the path of treating your husband like shit. You need to make this situation real for what it is now - you have fucked your marriage up and you need to take the morally correct next steps.
After all this if the OM is still on the scene then you can make decisions there in the clarity of your new situation.
Be prepared to lose more than just your husband. Some friends and family will turn their back on you.
You are allowed to leave a marriage, but ditch the deceit from now on and let your husband have his say in what comes next.