Rysmom, Please hear my heart on this. You have been posting over on MLC for weeks about this issue and getting some great advise. First of all, you do not know that this is a fact from the history on the computer. You are jumping to all sorts of worse case conclusions. Ads that pop up on websites are not necessaily indicative of what the person is searching or websites they're going to.
From what you're posted before, you don't have any emails to OW about any of this. You're basing your assumptions on ads on the webpage and what you say is his history. But you are not on his computer and have not installed a keylogger on his, you are only remotely accessing his work email. There are all kinds of problems with the way you are looking at it. At this point you are only driving yourself crazy with these assumptions and pushing your H further and further away.
Instead of continuing to drive yourself nuts, please detach and take care of yourself. Find some activities that you enjoy alone or in a small group. If you must search, I would hire a PI. If you H is contacting someone, they can find actual proof. That will give you the "proof" you seem desperate to find without you becoming a stalker.