Doug, as Yogi Berra would say, "It ain't over 'til it's over." The highest bid entered by the end of the auction usually wins. (There are a couple of exceptions, but they only happen rarely.) Thus, the other guy's bid of $125 would win out. When you (or anyone else) bid more than what's needed to take the lead in the bidding, eBay sets up what they call a "proxy bid" account where eBay will automatically keep entering higher bids for you, if necessary, until either your maximum amount is reached or your bid is enough to win, whichever happens first. So, the other guy's $125 would mean that he'd top your $100 bid by $2.50, the bidding increment for bids from $100 to $249.99.
