The chat function on his yahoo account is actually what alerted me to his second online dating profile. Not only did I check the inboxes on his email addresses AND dating profiles, but I also looked through deleted items, sent items, chats - everything and anything I could find. (For what it's worth, everything seems to consistently show that it started about a month ago) I've also checked our bank records and his credit card records. Cell records are not available to me, as the billing goes directly through his company, but I think I will ask him to try to obtain them.
I've become obsessed with trying to find more info, and I hope this feeling fades eventually because it's driving me crazy! I keep telling him I don't believe him, that there has to be more to the story, and he is maintaining that I know everything. Will I ever get to the point where I fully believe and accept that I've found everything?
I will be getting tested for STDs as well.
ETA: I've also added the yahoo messenger app to my phone and set it as "available", nothing has come up as of yet. He doesn't know what I've changed the passwords to on the accounts, and I've changed the password on my phone, so he can't get into it if he wanted to.