Why would I try to find my husband doing something wrong?

I seem to be pushing my hubby away. Sure, we have had our fair share of problems and, admittedly, most were the direct consequence of his actions. But after all this time I find myself trying to find him doing something wrong. I snoop all the time...looking for clues as to what he is up to. I try to find anything and everything and come up with a scenario for each thing. This is driving me crazy. Why would I do this? He has never cheated but just been a bum in general...like allowing me to work 60 hrs while 8 mos. pregnant while he pretended to go to school but instead stayed home and played video games...just as an example. I am trying to get over this...it was 10 years ago...but I still have this distrust. How can I stop myself before I ruin my marriage?