It sounds like things are pretty tough for all of you right now. :grouphug:
It does sound like your DS needs you right now. Whether it is because he needs you for math or not, it sounds like he at least needs to know that his mom is there to help him no matter what he needs. I am sure it is exhausting, but he may have concerns that he cannot express about whether you will leave too. Kids can view things so differently than adults, but can't always express them so they act out in ways that get them attention (good or bad). Is there anyone who can give you a much needed recharge/break during non-schooling hours so that you can be refreshed for HSing so that you can all enjoy it? It is tough to balance our children's needs and our own, esp. during a time of change and upheaval. I hope that you can find some help and support so that you can find a balance that meets both your and your DS's needs.
Also, maybe just some relaxed time spent together may help too. If you are able to do some fun things together and he has your undivided attention at other times, maybe he will be more cooperative during school time. That has worked for us here sometimes. Best of luck.