Welcome Nicki!
I think instead of thinking about it like you "should" have dumped him first, maybe you could look at it like he did you a big favor.
Changed attitudes aid recovery!
As someone with abandonment issues I spent way too much of my life with someone. You are ahead of me that you see through it so soon into the relationship. Hopefully you'll do better next time.
Thank you for letting me share!!
Take what you like and leave the rest.