Should i leave him over this?

Honey, don't leave him over this. Step back and try to look at the situation logically, and without emotion. He really has been tied up in knots over this for you. Can you imagine telling the bride, who is also immediate family, that you will "be bringing 1 guest to the wedding.. no wait, make that 3 guests... er, no, 1 guest.. nevermind, just me... wait a minute, 3 guests again.. " Of course he wants to just leave it alone. Try to see it from his point of view.