<human>: Can you provide a brief overview of the text?

I (21, F) ended a three year relationship in August. In September, I met a kid in class (22, M) who was pretty cool -- we started hanging out outside of class, and, after getting to know him and sharing some good chilling times we started fucking in November. We didn't get exclusive until Valentine's Day. He recently took me back to the house he grew up in for the weekend while his parents were out.

The problem? I don't trust him. My ex and I were really close friends for a year before we ever started dating. We knew each other inside and out. The current guy -- I have yet to meet ANY of his friends, I don't know how he interacts with other females when he's not around me, and I recently found out that he had a gf when we first started hanging out outside of class. We were harmless back then (just a midnight movie and a beer...) but the fact he did not mention her to me once really bothers me. What if he is out with some new chick from class right now? 

My single mom raised me to distrust all males and I have seen it ruin many decent relationships she's had and I don't want to repeat her mistakes. Yet I cannot rid myself of this sense of distrust 
so I ask you
<bot>: is it better to start with a clean slate, trust someone completely until they give you a solid reason to distrust them, or is distrusting any lover besides the closest friends the only non-foolish thing to do?