Let me start off...my husband and I have been together for 8 years, married for the last 6 years.

I was recently using his laptop and found an email he sent to another
woman. It just said "hey", but being the obsessive type that I am, I had to do every kind of search on the email address to find more info on this person.
All I came across was an AOL profile. I confronted him later that day and
asked him, "who is Leah?" At first, he said it was someone he went to church with. I asked him why he was emailing her. He wouldn't give an answer. He later went on to tell me that one night when I wasn't home a few months back, he had went to one of the clubs in town. He met this woman there, somehow she got a hold of his email address, and they had sent a few emails back and forth. He claimed there was "nothing there" because she had a fiance and that they weren't communicating any longer.
That information wasn't enough for me.

I started extremely obsessing over why this was happening and wanted
to know everything I could about this woman. I asked him to tell me her last name, he wouldn't. It came to a point where I was begging and pleading to find out. Eventually, I had to end up threatening to leave him over and over again, and he gave in.

First thing, I found her myspace. I had a problem with her right away.
She seemed to be everything I wasn't. It would make since why my husband might have considered leaving me for her. (Or at least that's what ran through my mind.)
I went further on to find out other info on her life, her marriages/divorces, and even her so-called fiance's marriages/divorces. It's become a routine thing to check her profile daily.

I've come to a point where I feel like I'm not getting the truth from my husband, as little of a deal as most people might find this in their own relationships, it's a panic situation for me. I know my husband's only friends, and they are all males.
He claimed that there was only friendship to come out of this, but he knows how I would feel about him being friends with a female, especially one he met at a nightclub! I ask him who talked to whom first, how long they talked, what the emails were about, etc. Since he had deleted all of them, and was sending all but one through his work email account.
He tells me "I don't remember! It's so unimportant to me, that I don't remember!"

I'm just looking for advice on what to do, etc. Should I take my husband's word for it and let it go? Do I have a right to be suspicious? Am I totally blowing things out of proportion? Please help.