It's hard but sometimes we as a whole all have to exp some of this until we find light at end of the tunnel I know it sounds cliche but there's faith right there trust yourself . Remember who you were whoever you were before the relationship before whatever bad happened ... Hope this helps!!
Busy yourself. I do it all the time.
It's a mindset thing. First you have to fully embrace and internalize the fact that you cannot change the past.
I'm not implying it's easy, but that's the first step. The rest will follow naturally.
Yeah same I've even got certain words that set me off thinking about the bad things in the past.
I don't know I find myself constantly doing the same thing. I have an anxiety disorder though so I can't really stop it.
I dunno, Jesus did it.
As simple as it sounds master 'Letting go' - and embracing the present.