So my ex texted me

So me and my ex broke up about a month ago due to him struggling mentally and also because of his schedule(he works nights as a nurse). Anyways when we broke up, he ask to stay friends. So he texted me Monday after not talking to each other for 3 weeks saying hey how are you. I haven’t answered him because Idk if I should or shouldn’t. I feel like because he is working during this virus, it would be rude to not text him back to see how he is doing also. Anyways what do you think? Should I text him? Would you text him if you were in my shoes?