My boyfriend gets mad if I don't answer everytime he calls me

Is this normal? We've been together for 8 years, he's currently in prison. He gets out in a couple weeks. The past 3 years when he would call from the prison phone I would stop what I was doing to answer bc I didn't know if that would be our only time to talk. Now I have a new job that is very time consuming, my son just started school back last week and I'm in a Masters program. He has a cell phone in prison now so he literally calls me 100 times a day. During work hours I have my phone on silent, when I get off work I'm cooking dinner & getting my son ready for bed. The past 3 weeks he's been going off on me for not answering everytime he calls bc he says if it were the other way around he would always make time for me. I've been working overtime due to an employee quitting and their position is still not filled. I feel like he's not being understanding & he tries to make me feel bad by saying "when I get home you're not going to have time for me so why are we even trying to make this work?"

All this was said last night, a few minutes ago I was laying do

wn to take a nap, he called and my phone was in the kitchen so I ran to grab it and by the time I got it, it stopped ringing. I immediately get a text that says "WOW" but I haven't called him back yet bc it pissed me off that he's mad if my phones in another room & I didn't want to call back when I was angry.

What should I do?