Dealing with PTSD Symptoms and Abusive Ex

I’m struggling with my ptsd symptoms and without going on and on, my ex lives in another state with my daughter and I can’t obviously cut ties with him but he’s just so abusive and I’ve gotten so much worse with my symptoms so I need suggestions on what I can do to lessen the anxiety and stress when I have to talk to him? I literally jump and yell out when I hear the notifications from him so it’s gotten really really bad. I have to communicate with him because she’s too young for her own phone and he hasn’t stopped trying to hurt me (he’s very successful at this) and it seems to have gotten even worse. So I know he isn’t interested in doing anything different for his own issues so I have to figure out how to change my own response/reactions and I have no idea how! I’m in talk therapy once a week and I see a psychiatrist once a month. I’m in recovery from alcoholism (4/19/18) and I just don’t know how to turn off my caring about what he says/thinks (“you’re a horrible mother, person, I hope you go to the liquor store and finally kill yourself”etc) off when he is so abusive and those are very small examples of what I hear from him on a daily basis. What do you guys do when you aren’t able to cut the most toxic people out of your life and any suggestions would be so awesome?!