At first Confused.. but now it’s making me kinda upset

Long post 😩. So, my sis in law ( my only brother wife) is going to be my matron for my wedding on 11/14/20. I got engaged on 01/2019 and my sis in law was automatically my matron so as you can see FH and I had a long engagement. Dresses was always black and colors always remained the same no change. Me and my sis in law have an extremely close relationship we talk every single day all day. We refer to each other as sisters/ best friends. My sis in law and my brother along with their 4 kids are moving into a new house in August/September 2020. They’ve been strictly house hunting for the past 2 months. I text my sis in law and even told her that I understand they’re trying to move plus with 4 kids that seems like a lot so if she would rather sit out of the wedding party and just help me the day of I will totally understand. I said that to ease her mind so she won’t have to worry about paying her dress, makeup etc. Just focus on their new house and her family. She replied and said she will still buy it, it’s my day whatever I wanted to do and whatever makes me happy. I said okay and just left everything alone went on with my planning plus I couldn’t imagine getting married without having her stand with me. Then I text her and I started talking about my planning so far to her. I get a lot of advice from her during my planning she’s always giving me advice, but this time she went completely COLD and that’s when I haven’t heard from her in 3-4 weeks and it left me confused . So I’m venting to my mom and FH about it and we all came to conclusion she could be overwhelming from the house search and the kids. So I didn’t text and asked was she okay I just gave her some texting space. So fast forward to father’s day on yesterday, my sis in law, my brother, their kids, and me and FH came over my parents house for father’s day dinner. My sis in law didn’t talk to me IN PERSON not one time! It’s almost like I felt extremely ignored. She laughed, enthusiastic and talked with everybody else, didn’t say not one word to me. Didn’t say bye, hi... nothing. FH noticed it when we got home and first thing he said was “ your sis in law was acting so weird, she didn’t even talk to you”. And I’m glad he noticed, so I went from confused to extremely upset! I have no clue what the heck is going on, I didn’t do anything and I’m not too happy about it. At my parents house she was on her phone ( along with everybody else as usual) when we all were just chilling watching Netflix so it’s like okay I know you saw my text 3-4 weeks ago. She was holding my nephew and I was waving saying bye to him like we always do when we part ways, my sis in law kept walking, when I reached for a cup to get a drink she came on the side of me and said “ oh I was looking for those cups” and as I’m reaching to get my cup, she doesn’t even wait until I’m done, she takes the packs of cups in a small snatch. And that right there was the final straw I have no clue what’s going on or what to do. I know this is long, but any advice or thoughts? I’m ready to just say she can sit out. I’ve already decided that she will not be holding my bouquet even though she was at first.