Having to pee badly at work.

L
I'm a legal secretary for a law office. There is only one other person that works with me besides the attorney. She is currently out of the office today and we have a deposition being held in our office today. I have to stay in the office and help whoever needs it and man the phones and other clients that come in. I have to pee sooo badly that it hurts but I can't leave or interrupt my boss as she's in the middle of giving a deposition. Has anyone else been in a position like this? 
*I'm currently 24 weeks pregnant.