Do some reading on trauma bonds and the cycle of abuse.
I split with my toxic ex too many times to count, I used to feel like I was dying and couldn’t go a day without breaking and contacting him. I ended it, for good, some months ago and although he has occasionally popped back up declaring his undying love for me and promising the earth, I’m no longer interested. I deserve far, far better and actually i’d rather be alone and at peace than with him.
You are addicted to the highs and lows, you are withdrawing but I promise if you stick with it you’ll come out the other side. Don’t waste years more of your life.
A very wise poster @thefoundations gave me lots of advice when I posted under another user name and even a year on it’s been invaluable. One of the posts that stuck with me was all of the anxiety I was feeling, all the confusion was because it was my body literally rejecting him. Like how your body physically reacts when you get food poisoning trying to flush it all out, that was emotionally what was happening to me. He was literally a poison to me.
It will be hard, it will feel impossible and your brain will focus on the good times you had but you can do it.
You have to do it. What’s the alternative?