1. yes. this is the most normal thing. i’m sorry, i wish it weren’t.
2. you need to not talk to her. not forever, if you don’t want to, but definitely for now. i’m going to say at least 1.5 months for every year you were together, 3 months minimum. you probably will not feel much better after those months but i think you will be sleeping a little better, and will be better equipped to recognize how interacting with her makes you feel. but for now, block her on gchat, delete her from your phone, everything. make a friend do it if you can’t. then make this friend your accountability partner, this is some AA level shit here. if your ex doesn’t understand, maybe she should have thought about that before breaking up with you.
3. the only place to go from here is forward, onward and upward. you will do this even if it doesn’t seem possible now. the only way out is through.