Why do I read too much into stuff?

For some reason I have this extremely bad habit of always thinking the worse and thinking stuff are not what they seem. For example there are things in a personal relationship that have bothered me for years and I have always thought the worse about it and then when the worse happened I thought my life was over. Well I got over it but I still can't help to go back to that line of thought and stop thinking these things. It is almost like I am being destructive even though I have no intention of it, it just happens. What it honestly boils down to is the fact that I need to give in completely and trust. I do trust but I am very scared and just afraid that I will be stupid and something will happen right under my nose if I don't keep my eyes open. Ugh just more of those thoughts that I need to erase!!!!

~sharon