This is >>494 speaking.
You're actually a lot luckier than you give yourself credit for. Sure your significant other's now your ex, but now more than ever you've gotta count your blessings. After all, unlike me, you've still got the chance to hang around other people and socialize on the 4th. It might not be Valentine's Day, but it's still depressing to spend any holiday by yourself. Enjoy your company picnic to the best of your ability, okay? Have fun with your co-workers, and stay positive. If not for yourself, for all those people who don't have anyplace to go that day.
I know what you mean about being annoyed with people holding hands and whatnot. My best friend invited me to hang out with her college friends(we go to different colleges) and her boyfriend for her birthday, and it was the worst day I ever had. There were five people including me. There was my best friend, her boyfriend, and another couple. It felt like I was intruding on a double date the entire time. My friend wasn't very considerate at all; she kept kissing and hugging her boyfriend. After mini-golfing for a while, we went to her boyfriend's house for cake, and they just rolled all over his basement floor making out the entire time, for hours upon hours. I sware, people have no modesty these days! It's like they were practically about to have sex in front of me. I don't mind kissing or holding hands, but please, there's a limit!
Don't get me wrong, I love my friend to bits, but she gets on my nerves sometimes. The thing is, though, we've been friends since we were kids, so even though I hate how much she loves her public displays of affection, I want to support her, because it's her first relationship, and your first relationship is the one you always remember. Whether it was good or bad, you'll always remember it.