I am so sorry for your pain.
This kind of situation can turn your whole world upside down. The anxiety, the unknown, the sleepless nights, the lack of self esteem, the over thinking thoughts & you just literally feel numb. Let me tell, this is the vulnerability in you when something like this first happens. All you want is them back, your back & the love back. I went through it but pulled through but it was the hardest thing ever.
Let you me share what I learnt not once but on a few occasions when trust was broken due to infidelity.
You just want them back but really it's not them you want back, it's the love and the fear of abandonment that keeps you trapped in taking their rubbish. The more they see you very broken apart, the more comfortable they feel doing what they do because they know you will still be there if their dirty affair fails.
They always come back if they are the type to be dishonest, a history of cheating & narcissistic . Once they come back, don't mean they will change unless they take full responsibility of their actions looking deeply within themselves. So what did I do? I fell apart for months even maybe for year until I did something for myself, I let them carry on with their seedy life. Once he saw I got a grip & was stronger than him. He wanted to come back because I no longer gave even the slightest fuck. If you have children, don't let this force you to try and connect the family back together unless he changes.
I can't tell you what to do but once a cheater always a cheater especially if husband works away which was in my case. Don't waste your mental energy, it's okay to break down but it long term it achieves nothing. Take your time but eventually stand back up & show him you will be okay & that you don't care anymore. You have the children that you need you, you need you and nobody else can give you the happiness you deserve except you.
Two things will happen from this :
He will continue the affair for as long as possible til the novelty wears off, the sex no longer excites him. Or the affair partner will except him to leave you & he will be in conflict with that. You let him do as he likes. You will only think of yourself & you do what is best for you & only you. Don't not show him you want him back even if you do. If you do wish to take him back . Let him come to you without pressure or force. It has to be done naturally.
2nd outcome could be that he may want to stay with his side chick but will cheat on her too because that's his form now! How do you know he hadn't done dirty deed previously whilst married to you. I didn't consider this regarding own situation but now I believe there was many occasions he did it before unknown to me.
You can message me anytime for support as everyone is right on here. It's the only thing to get you through.