Picking up, welcome to the site. I am truly sorry that you are here under these circumstances, but generally people in happy marriages never seem to find their way in here.
I completely understand how you put so much into a relationship with one person, only to be repaid with cheating and hurt. I also understand that the pain feels unbearable and like there is no hope of it ever getting any better. I have totally been there.
my wife was the absolute center of my universe. I struggled because I felt like I could not come up with enough ways to worship her... then she cheated on me. I was devastated. I cried so hard that I couldn't even open my eyes. I couldn't get off of the floor and my ears roared so loud that I couldn't sleep. My eye lids hurt from crying so hard. I became the most pathetic and miserable excuse for a man there ever was.
Let me tell you. That does pass on and go away, but only when you go through the process of the grief. There are 5 stages of this grief;
Denial – The person getting broken up with is unable to admit that the relationship is really over.
Anger – When the reality sets in that the relationship is over, it is common to demand to know why they are being broken up with. This phase can make them feel like they are being treated unfairly and it may cause them to become angry at people close to them who want to help aid the situation.
Bargaining – After the anger stage, one will try to plead with their former partner by promising that whatever caused the breakup will never happen again. Example: “I can change. Please give me a chance”.
Depression – Next the person might feel discouraged that their bargaining plea did not convince their former partner to change their mind. This will send the person into the depression stage and can cause a lack of sleep, eating and even disrupt daily life tasks.
Acceptance – Moving on from the situation and person is the last stage. The person accepts that the relationship is over and begins to move forward with their life. The person might not be completely over the situation but they are done going back and forth to the point where they can accept the reality of the situation.
I am still married to the same woman who cheated on me, but she has been replaced at the center of the universe by my kids. She is still in there somewhere, but not nearly in the position she once was in.
You are making the right decision in letting him go and forcing him to live with his decision. This will pass. In the meantime, focus on YOU. Become friends with YOU. Live for YOU. Anytime that anyone places the burden of their happiness on someone else and trusts that that other person will do right by it is headed for disaster. Find your happiness from inside yourself.
I know... there are no words that can make it better. There aren't enough hugs or words of encouragement to ease the pain. You feel as though none of us can possibly understand how it is for you. I know this because almost 3 years ago, I found this site just like you did. And while the caring members here told me the same things we are telling you, I felt like they were full of it. but later, I found out that they were right!
Most of the members from that time have gone silent on this site and moved on with their lives in one way or another, but just know that you are not alone! Sometimes that's what it takes to feel better. Knowing that you are not alone.
Take care of you!