Sorry to hear you are going through this. If I had to guess, I'd say your son is hurting too and that is why he is acting out. It's possible he feels he's lost his strong capable dad and that his strong capable mum now seems so unhappy and not like the mother he imagined could solve anything and perhaps he feels that now he has nobody he can turn to.

Don't get me wrong. It's not an excuse. You are a person too and don't just exist to be a support for him but if he's usually a decent person and this is out of character for him, it may be that he is struggling to deal with the upcoming role reversal. Both your sadness and his father's death together may have reminded him that you are not invincible.

It's scary to think your parents are just other human beings, that they don't have all the answers and that they need support themselves.

Not that any of that justifies him not talking to you for months just because you were grieving, but it may be an explanation. Unless this is typical behaviour for him in which case, yeah, he's just being horrible.