In the past, I've seen the game take money from other places or just push you over budget to auto arb your guy. If it does push you over budget, you won't be able to make any other moves until you get back under budget. I'm not sure on the order of how it processes stuff, but if I had to guess, I think you'll keep your arb player, get pushed over budget and your other trades will be nullified. But as jahu43 said, the best thing you can do now is wait.