Should I continue to keep my 3 yr old home or let him go w/ his father and gf?

I've been out of work for almost a week now due to the covid-19 pandemic and my job closing school for two weeks. I'm usually ready for my break every other week when my 3 yr old soon to be 4 yr old goes to see his dad, my ex husband and his new gf, but I have had him at home all week with me and I'm scared to let him around his dad who works in the hospitals & gets coughed on by patients (even got sick twice while we were married was sick as a dog from patients coughing on him) and his gf works as a nurse as well. I don't knw her schedule or if she works on the weekends, so to be on the safe side, I told my ex I would just keep our son home with me this weekend so he won't be exposed to his or his gf's possible germs from work. He took it the wrong way & he & his gf are lashing out at me. He's abusive towards me and that's why we're no longer together. He thinks I don't want our son around his gf, but like I said I really want a brk this weekend, but my ex isn't responsible the least bit. Our son is potty trained, but is too lazy to put underwear on him that I send him so he puts him in pullups still, he (our son)fell down the stairs back in the summer and he failed to tell me, so our son & my ex father in law told me. He had a huge knot on his head for 2 months. He drove off & left him at the fire station during his last visitation drop off & my son was standing there screaming & crying. He was being an @$$ & wouldn't drive him to my car and left him @ the entrance.