Husbands work Christmas party update.. mixed emotions

My Husband just recently started working at one of his old jobs again and when they did their Christmas get together, it was in the morning at the office. This year it's at a restaurant. I kinda don't wanna go because his friend will most likely be there with his pregnant girlfriend who I feel always rubs her pregnancy in my face.. this month is already hard on me as it is but my husband really wants to go to this dinner Thursday night. What should I do? What should I wear? I've not met many of these people because they are all new... ugh I hate meeting new people and being around people in general.. Help?!

Update....So my husband and I went to his work dinner last night and I must say that was the most awkward thing for me! His friend and pregnant girlfriend weren't there so that was good. But there is this girl that works in the office that called my husband on his personal phone a few weeks ago ( I think I deleted the post I made about that one) but she was there solo at the dinner and for a woman who has a husband is awfully friendly with my husband.. she stared at him the whole night and was always talking to him or making jokes towards him at work.. and her and her friend that also works there were doing quiet a lot of whispering.. I just stayed quiet and stayed on my phone a majority of the time. I've never felt that awkward around people. But now I have a bad guy feeling about this girl.. my husband said I have nothing to worry about but I feel like he doesn't care about what happened nor cares about my feelings... we shall see what happens..