Bathsheba that is so true. I spent years being angry at my mum (different issue ), until I realised that it was taking up a lot of energy & effort to stay angry, I really had to work at holding onto it & it only made me feel like crap. As soon as I let go & started to accept that she is not perfect & she probably had regrets over that particular incident, I felt like a huge weight had been lifted. It was a great lesson for me; I was never really one to stay mad but this particular thing was so bad I didn't think I would ever get over it - but I did.
Anger serves a purpose in the short term but long term it's kind of useless - JMO.

Lara, I also wanted to add - I am not perfectly warm & understanding all the time - I still have to work at it sometimes. I quite often grumble about the rude person I encountered before asking myself if there might be a reason they are having a bad day! I think that's ok don't expect too much of yourself. The fact that you want to be more compassionate & understanding gets you a long way there, iykwim.