I doubt very much that UC Riverside will give you money that it collected from your husband. Its not their job to transfer money between spouses. Your son probably has signed a housing contract. At this point can he withdraw for next semester? I know at my daughter’s school it would be too late.
You are probably going to have to get a job. Being a mother doesn’t mean you can’t work. I am a mother and I always worked except when I was on maternity leave. You are lucky that you have been able to go so many years without working, but it sounds like that is going to change. You are an educated adult with a current license in a marketable field. Its time to start thinking about getting a job.