Communicating with someone who never truly listens

Miss sons dad and I have recently not really been talking since I told him I am having another baby (not by him). My son is 7 and we have not been a couple in 8 years. After I told him I was pregnant, he really stopped communicating with me (we used to communicate daily and got along pretty well). He hasnt really spoken to me in 4 months and hardly calls my son. I stopped reaching out to him bc I knew he didnt want to talk to me (why poke a sleeping bear...really bad breakup history). I have never ever blocked his communication with my son...he can call whenever he wants but rarely does.
Anyway, He sent me a long email yesterday and I am debating on whether or not to respond. He is very narcissistic so he never admits he has done anything wrong and has always refused to hear anything else than what he already believes. Part of me wants to respond and tell him the role he has played in everything but part of me feels like its a complete waste of time and why should I even entertain this nonsense.  What would you do?