What do i do???

I am currently engaged with a man ive been engaged with for 3 years and have been dating for 5 years. I think of him as my bestfriend, i just seen on our computer that he has signed up for yahoo personals. i know he loves me and he would tell me if he wanted this over. should i be mad???? im so confused on what to do. please help. i know his pword to everything and ive seen that he signed up for this so what should be going through my mind???