Yes, he can if you have maintained separate addresses for at least a year. Isolated instances of sex do not reset that clock.
FWIW, I'm so sorry for your loss. If your husband truly intends on going through with a divorce then he needs to let you alone so that you can heal. What he is doing is, in my opinion, very cruel and selfish. If he won't go for couples counselling, then please, go find a professional to talk to for yourself to help you deal with his poor behavior. You deserve to be treated with more respect.