He spent our money without asking

My husband and I opened a joint account to pay in the cheques we were given as gifts from our wedding. We had agreed we would use the money for something special so it was kept in a separate account which we are both named on. I was thinking about using it for the night away we have planned for our anniversary and asked my husband how much we had to spend - he has internet banking but I don't. His response was nothing at the moment as he has "borrowed it". I asked him what he meant by borrow and he says he is going to pay it back at the end of the month. Am I wrong to feel completely betrayed by this? I feel like I can't trust him anymore. He is so bad with finances but I feel like this is stealing. He says he will pay it back but I wonder if he would've had i not asked about it.