You get through it by being kind to yourself and honouring your need to stay away from this person.

Mindfulness exercises can be really helpful, when anxiety becomes a problem. I have a link to a really funny one (it does contain some profanity). Let me know and I will share the link here, if you can stand to hear a few salty swear words)

Each day gets a little better. Remember you are changing what was likely a bad habit or repeating pattern with this person, so the longer you are able to maintain no contact, the better off you will be, until one day you get to a place where no contact is no longer a state you are in, it is simply you getting on with life. Wish you well with that.