Taking another women to his Xmas party

Nichole

So my boyfriend of 17 years (we have a 10y/o and a 6y/o.) ask our friend to go with us to his family Christmas party. He decided he didn’t want to take the kids this year even though it’s at a family friendly place the kids had a lot of fun last year. He just thought it would be nice for us to get out of the house with out the kids. I was cool with it that but then he said he invited our friend (female)to go with us. Now I don’t want to go. We never get time alone and I know if tell him this then it’s gonna cause a whole thing and him not have fun at his Christmas party. If I do tell him and he disinvites her I look like the asshole. Are my feelings valid and shouldn’t she have known to decline the invitation she knows we never get time alone. She get more time alone with him than I do. She doesn’t have a car so he will pick her up on his way home from work to come hang out. I just want to know if my feelings are valid or am I over reacting?