Do I let it go one more time for my son?r

I’m torn on what to do. I was married for 14 years. The divorce was my choice/my fault or whatever you want to call it. The marriage was toxic from the start and we are both much better off now emotionally and mentally…. That being said, we married young, my parents helped us live so he could go to college and get a degree, which he did. We owned a very profitable business together. We have 3 kids together, 2 younger and 1 in college. In our divorce he was suppose to buy me out of the business for a large sum of money. That never happened. He made payments for about a year, and then nothing… including child support. He ended up spending frivolously, for extravagant trips, race horses, medical procedures for the girl friend. Etc…. And ended up losing the business and assets. He was then “jobless” for over a year. Now he has a job again, but has filed bankruptcy to get rid of the debt he owes me, because if he has any debt, he apparently can’t keep his job (security issues). The debt he owes me is too big to discharge in chapter 13, so now he has to move to chapter 11. He will still be able to discharge his credit card debt, and other debts, just not mine… here is the problem. Our oldest adult son has given me the cold shoulder over all of this. His dad has involved him in all of our business, since the beginning, and has made it very hard to have a relationship with my son. My husband and I pay for everything for my oldest son (tuition, rent, phone, bills, food, gas money literally everything) his dad pays for nothing. I work, and my husband works, and we do live comfortably. My son sees this and thinks that I just need to give his dad a pass. My ex mom in law says I’m greedy and that I need to just forgive the debt and move on because it is the Christian thing to do, and because I don’t “need” it and because it’s probably the only way to have a relationship with my son. My ex is married to a girl with 3 kids of her own and they have 1 together, he has a very good degree and makes a very good living. My son feels it’s unfair to his dads “new” family that I “hold this over his dads head” and feels like it is my fault that his dad might lose his job. The way I see it is that I gave up 14 years with this man. I supported him and was very involved in building what we had. All the checks written during that time were to him. Never me. All the taxes paid (think social security) and so forth were paid under his tax ID. I was never able to finish school, or have a job or career of my own, other then doing all the office work for our business and basically raising our kids as a single mom. Point being, I have nothing to “fall back on” at the age of 40 and some change. I did try to work with the ex on making a payment plan to help him keep the job. I just refuse to write off the entire amount, and he refuses to work with me. So do I stand my ground, and hope someday my son is mature enough to see that there are 2 sides to every story. Or do I just let it go, and let the ex screw me over 1 more time, for the sake of my son….which in all honestly, I don’t know would even make a difference since the ex poisoned his mind years ago. Its just getting old that every time any issue dealing with court or his dad comes up, he just stops talking to me. I’m hurting and heart broken over all this, because I love my son, even if he doesn’t love me. Any advise is appreciated.