Ex calling from jail what do I do

I broke I’m with my ex on Jan 1st. We had a toxic, abusive relationship but of course there were good times with it as well. I haven’t talked him since then. I blocked him on everything and deleted everything. He messaged me just about every day off different numbers usually just saying my name or telling me it’s been so long or asked for sex or to tell me he was talking to someone. We were together for 4 years, he knows where I live, where I work, everything and the most he could do was text me my name. Now he got arrested and is in jail and keeps trying to call me. I haven’t answered. His friend called me and told me how he wants to hear my voice and talk to me as a friend bc im the only one who can calm him down. I don’t know what to do anymore idk if I should answer. I feel used all over again. I feel bad at the situation that he is in and I wish I could help but he hurt me so much and I haven’t talked to him. I don’t want to get sucked in. I feel so guilty for not being there for him but at the same time I need to be there for myself. Please help me I need help more than anything