"I kissed her and found out she had mono now what do I do?"
Don't kiss anyone else on the mouth until the person you kissed is all better from her illness. The incubation time is 4 to 8 weeks following infection with mononucleosis. Kissing someone on the lips is risky for several diseases so try and use common sense when accepting this risk.

"How long is she contagious for?"
The rule is that a person can still transmit mononucleosis for 3 weeks from the time she feels all better. So if your partner has mono in December and feels normal on January 1st, consider that she is still actively contagious until January 21st. There is some evidence that Epstein Barr Virus which is the primary virus which causes mononucleosis can be shed or transmitted from the throat for up to 18 months after an infection.

"Is it okay to wash her silverware in the dishwasher with the rest of my dishes?"
Yes, there is no risk that mononucleosis will be transmitted this way.

"My room mate has mononucleosis, how do I know I won't get it?"
This disease does not readily transmit to non intimate household contacts.

"How common is mononucleosis?"
Evidence can be found on blood testing which shows that about 90% of the population has been exposed to the Epstein Barr Virus which is one cause of mononucleosis at one time in their lives.

"Why can't I play football or hockey if I have mononucleosis and feel fine?"
Contact sports are restricted during and after this illness since the spleen is enlarged and if impacted can rupture. Your doctor will obtain an ultrasound which measures the spleen and when it returns to normal in a few weeks you are set to go back to contact sports.