I'm really sorry this happened to you...but it doesn't surprise me. Some of my co-workers were the most insensitive to my situation and they knew what I had. There were only a couple of them but they made it their business to have a comment about anything that concerned me and my MS dx. Of course, they never take it upon themselves to try and learn something about the disease....they just like to gripe about the supposed "perks" we get because of it. If they only knew.....

Stand your ground. Especially if the picnic is on the weekend. Unless it's in your job description and agreed to by you they can't tell you what to do on your days off.

One last thing....if they are truly getting drunk at a company function your employer is taking a huge risk.