You need to ask yourself why she felt like she had to hide his gender from you. Are you controlling and jealous in other aspects of your relationship? Have you may controlling or jealous comments about make friends in the past? That may have been why she waited until the last minute to reveal the gender of her roommate. I think your concern should be WHY she felt the need to hide that piece of information.

I think you absolutely have a right to feel concerned. However the way you are reacting is extreme.

I think it's reasonable to have a conversation and address why she didn't tell you until the last minute. I also think it's reasonable to lay out your insecurities as long as you take responsibility for them and don't place the blame entirely on her.

I think with open and honest communication (and you meeting the male roommate) this may be something you can work through.

I've already touched on the fact that you don't know this guys financial situation. For all you know he's work all through school and has ample savings to pay rent. This is also something you can discuss with her too.