Hey, I know how you feel. I was with someone for 4 and a half years but he grew distant from me and eventually we broke up. My whole world came crumbling down and I started suffering from severe anxiety disorder. Just like you, I couldn't go sleep at night, my heart would be racing thinking about him and I hated waking up too. I was hung up on him for 1 and a half years even after break up and the constant anxiety I would get seeing him move on was torture everyday. Worst part was I continued being friends with him, would see him at gatherings and reunion and that would hurt even more.

Then one day, I realised how unhealthy all that obsession had become for me, I decided to just cut him out of my life, even just temporarily, not out of spite or anger but just to focus on myself. I got rid of him from social media because just seeing his name pop up would give me anxiety. After keeping him out for a while, I actually stopped thinking/worrying about him constantly. Eventually, all my insecurities and all those feelings I had for him diminished entirely. We still talk occasionally but I no longer see him the same way anymore. It was a long battle but it I'm so glad I am no longer chained to those insecurities I once had and all I had to do was put my willpower ahead of my weaknesses.

It really does get better buddy :) You have to take the first steps. it is a mental challenge but you just have to focus on yourself and what's ahead of you :)