Casey, you are behaving like a politician, with half-answers and sort-of apologies. Find a way to get the mouse you stole back to Christina, and do it now. No more excuses or stalling, please. You stole and lied, and now it's time for you to man up and correct that. It's that simple.
The longer you take and the more excuses you give, the more you suffer and the more your mouse organization suffers (you're the President, for Pete's sake).
I agree with and fully endorse this sentiment. When I was young I did something really stupid. I only did it once, but I felt guilty and got caught (as I should have). I immediately paid my restitutions (so to speak) and apologized, full-stop. No excuses. I remember that it was very humbling, but in retrospect I learned a hell of a lot that I can still apply to my life today.
There's a lot of value in saying, "I did something wrong. I'm sorry. What can I do to make it right?" and then doing that.