Some info for context.
Best friends from school 20+ years. Friends in a group aswell as separately.
Grown up together. School uni etc even worked together a while. Both with significant partners and 3 children each. Kids are friends. Same school etc. Same stage of life basically.
However, I just think she has gotten so argumentative. I'm pretty easy going but even this is starting to annoy me.
If I said "Aw thats so nice your mum is babysitting the kids will have a great day" she'll reply with. "Well who did you think was babysitting" or another example is we were out for the night and had a few drinks and someone said to her oh what time you going home at? I answered and said we've a cab booked for 1am. I know technically I answered but we were all sitting together. She would snap saying "can you butt out" this is all the last few months and I can really see her picking up her partners argumentative traits. Not traits I've seen in my friend for the past 20 years!
Other in the group have also noticed, and have stopped bothering much with her. I don't get into the gossip about it because I'm obviously loyal to my best friend.
I don't know how to deal with this?!