"It was my first job as a developer, and when my boss left I got promoted to "CTO" and got to hire my own small team. This is one of the main reasons I haven't really "gone after them". I don't really want to screw them over, I just want my money."

Did you deserve the job of CTO? If so, then you also deserved the paycheck. If not, then be happy with the fact that you got a cushy job that will look good on your resume and leave it at that.

Seriously, this is business. It's good to be happy about the time you worked there, but don't let it cloud your judgement. I'm not saying you should go after them. I'm just saying not to hold back because you feel you owe them something that you don't.