Sorry for your situation brother.
I know it sounds cliche but:
1) It is not the size of the home, it is the love inside the home. I have heard over and over stories where people said the happiest times in their lives were when they were scraping by.
2) Education for your kids starts at home. Your kids will learn from your love and kindness.
I walk most mornings I am home with a buddy who's first wife abandoned him for another guy and ran off - leaving him with two young kids.
He was totally devastated by it and had to change everything to get by without her.
The two kids are grown now and both turned out great and their love and respect for him is very apparent. I see them when they are in town and they are great kids.
You are 20 years younger than this old fool posting this reply. You have many years ahead of you to recover personally and find someone better.
I don't want to belittle the pain you are going through. I went through a lot of it myself. Just a little over a year after my dear father died, my wife became very distant and I soon discovered why.
People here will help you through this. Please focus on your health and your kids.
I am in fairly good shape and had to go on blood pressure medicine, anti-depressants, sleeping pills and even my testosterone hit rock bottom.
I have rebounded very well thanks to the love and support of many and so will you.
Focus on your tasks at hand and try your best to control your thoughts. When you start feeling sorry for yourself, think about three things you are happy about.
Be thankful for your great kids, your other family, your friends, good health, hopefully a good job, etc.
Things could be a lot worse.
There are a number of women on this forum that have been abandoned during their pregnancies. They have other kids to take care of and no job. They face tremendous financial pressure.
That is rock bottom....
Please trust me. Things will get better...