How do I keep from crying?

In a few hours, I will be escorting my daughter during their last home game to recognize her as a high school senior, and I've been an emotional train wreck to think this is the end of this chapter. How do I keep from crying during this event soas to not embarass her (any more than I already do).

By the way, she's a tough cookie -- as in 'broke her finger duing a match but continued to play until the ref kicked her off the field for bleeding, whereupon she got it taped up and subbed back in to finish the game' kind of tough.

Of note: Recently I've been diagnosed with an autoimmune disease which has altered a number of hormone levels, which adds to my weepy-ness. Not trying to make excuses, just trying to paint a full picture. The last thing I want to do is make a scene or break down...but just can't figure out how to keep it together.