I know that jealousy is bad but what do you do when you keep geeting crap thrown in your face?

Its been two years with my boyfriend. In that time we have had our ups and downs. He has soo many ex girlfriends and female friends and it drives me crazy. I try to trust him but he just goes and does stupid things. 1- When we first got together maybe after about 6mon he told me that he was going out of the country camping with friends did not mention that his ex was there, the one that calls from overseas 4 him send her items because no one else on this earth is as dependable as he is. PROBLEM. We got over it... maybe I should say I tried to get over it. 2-The ex and friends are in town..so surprise she came over..for some odd reason I could not reach him and then boom.. found out she was there and had spent the night...of course becuase several friends where there nothing happened.RIGHT 3. A "friend" needed him to fix her computer..fine..from 7p to 11p? I let it go.4-The same friend came by to get her comp fixed and how about she forgot it! But just hung out til 11:30? Is it me???