I was exactly like you before I decided to file my divorce. Once you made up the decision and finally file the petition. You will be cleared you mind and you will need to concentrate to deal with your solicitor. You need to fight what you and your kid's best interest and what you are entitled to - Custody and most important Maintenance for you and your kid. Trust me, I just have been thru all of these.
Be strong, it is not the end of world. It's his lost not you!!
I have the same story as you. My ex and I have been together for 15 years. He is the one have numerous affairs but blaming me for everything. I was abused, bullying by him for so long time.
My children and I actually moving out next Saturday. The place we are moving in is only 1/3 of the size. And the maintenance from him plus my salary are much tighter, but one thing that I am absolutely sure is my children and I will be much happier.
So we all have to be strong and be positive that's I can think of, life needs to be moved on. Being happy or sad is entirely up to 'YOURSELF'.