Is it ok for my husband to be to be friends with ex girlfriends on facebook?

I can see how some might say I am being insecure or immature...however the fact that I am aware of these emotions; and I know i can handle them differently. Doesn't dull the pang of anger that pierced through to my stomach when I saw an ex girlfriend leaving messages to my fiance on Facebook ( our wedding is 2 months away). Not to mention He hides things from me all the time-- little things and silly things...which I don't understand its almost as if he enjoys having a "little secret" so excuse me for feeling this way but I am 8 years younger and I have been the main source of income and I am also the main housekeeper and child care giver (we have a 9 month old). I do love him but sometimes I wonder if I can really trust him. its gotten worse the closer the wedding gets, I am scared. I just need to know if this is irrational about him having ex girlfriends on his facebook....thanks and please try not to be rude.