Bad relationships you stayed passed the used by date in, jobs you've hated, in lines you waited, advice you gave that friend didn't take, plans you made which didn't eventuate, when you've been late and thought you missed out on the best part of an event, those times you decided to vent and the outcome didn't change, all of those years you placed blame. You may feel none of it was worth it, and what a waste.
The thing is you were constantly learning all throughout this time.
You knew not to go for that kind of guy again after leaving, and became more aware of what you do and don't want.
That job made you realise a thing or two, and it deciphered the who is who or altered how you are you.
As you waited in line you were forced to stop and observe. And didn't you learn?
That advice you gave came from a place you probably didn't know existed, and although it didn't work for your friend perhaps for you it was more fitted.
You may have arrived at exactly the right time, and at least you showed up and didn't decline.
Sometimes the only ones who need to hear what we have to say is us, and then it's to ourselves the responsibility to change a situation we should entrust.
There is never a winner amongst the blame game. All that comes from this is shame and things just remain the same. Perhaps when things don't change you can see that it doesn't work, and blame is far from what anyone of us deserve. You did learn.
Don't bother with the should have could have and would haves...it's nothing but a trap. Give yourself a metaphorical slap and wake up from the lies you keep telling yourself. Place all bad thoughts and memories back on the shelf. Only take what is useful to you.