The last 3 years was a process you had to go through to get to where you eventually want to be. A very efficient process that not too many others ever get a chance for.
Every time I had a tough gig, instead of focusing of the jerk I worked for, all I thought about was what I was learning and how I could leverage that into my own future. That kind of thinking has always worked well for me.
You now have the background, experience, and skill of an accomplished 35 year old in a 25 year old body. Congratulations!
Now stop worrying about the past, take a short break, and put those hard earned assets between your ears to work for what you really want. This time next year, I hope to see a "Tell HN" post from you, "How I turned 3 years of sweat into a lifetime of fulfillment."