Am I overreacting?

I just want to get some additional opinions. My husbands brothers fiancee has been on my last nerve for a few months. She's made a few comments and done some things regarding my husband that have made me feel like she doesn't respect my position as his wife. The first event was during a shipping trip with or mother-in-law, in which K made a comment about getting the boys (our significant others) milkshakes from a specific place, because Brent (my husband) really likes them. My initial thought is, "why are you going out of your way for MY husband?"

The second issue I have is that when she and my mother in law are together, if my mother in law can't get a hold of my husband, K decides to chain call him, as if he's more likely to answer for her than his mother?

The straw that broke my back was that she didn't say a word to me on Mother's Day (I'm expecting), but texted my husband on fathers day, wishing him happy Father's day and expressing how excited she was for him to hold his "little peanut" for the first time.

Am I out of line for being really irritated about these things?