I just dumped my girlfriend of three years. Was it the right thing to do?

You did the right thing. This is a Preview of what you would have married and had to deal with. The only thing is,, when you get married things usually will get worse not better.Take it from me I married someone like this and it was soooo hard being married to someone where if I spoke to someone of the opposite , he would not NOT talk to me for days..You are LUCKY you dodged a bullet she is not the only woman in the world, take some time and work on you, every day will get easier and wait on the person who will truly make you happy. Life is hard enough without volunteering to be miserable. We want things to work out with someone and when they don't we think holding on makes us strong but sometimes its the letting go that makes us really strong.