Filling Separately when still married

I am still married but I am filing separately as my divorce is taking over 2 years. I can't claim my son's education expenses or anything even though he lives with me going full time to a University.  The courts ordered me to pay alimony and that doesn't even count unless the year goes back to 2018. What can I do? I have to includes expenses. My son is 22 and does not work. I basically pay everything and alimony. Suggestions?