It took a lot of time but I started to find other things that helped - I started trying new activities and finding people who had similar interests that I could turn to and focus on when I was stressed.

I found that for me writing also worked really well. Instead of having things in my head that just continued to spin around and make me more anxious I would write them all out - anything that came in to my mind. All of the negative thoughts and ideas and the replay of what had happened that made me frustrated. It helped me to get it out.

From there I would find a way to destroy it - rip it up, put it in water so it fell apart. It sounds strange but it was a physical way help me remember to let it go. It didn't exist any more. If those thoughts kept coming back to me I would remind myself that I had dealt with it & let it go and try to move to another activity that I found enjoyable.

It sounds strange and it did take a lot of time and practice but it slowly got easier to let things go. Now I very rarely have to write things out as I have learned how to let things go without becoming that stressed and irritated. It doesn't work for everyone - it really depends on your interests - but might be something to try