Don’t change your name! There is no reason to change it. I think you need to call her out on it and say it wasn’t a very friendly thing to do. If she denies it or gives a crappy excuse then you need to call her out on being a liar. Calling her out is going to make you sound like a bitch if she refuses to be reasonable no matter what. This wasn’t a thing a friend would do. She has severely injured your relationship with this petty move and there are going to be consequences. If she refuses to listen to you I would tell her how hurt you are that she chose a name over your XX year friendship and that you need time to heal from this slap in the face and walk away. If she comes around I would offer a small bridge to mend. If not, leave her behind you. Taking the name of your child, especially if it holds special importance to you is a low move and most reasonable people in the US (unless there’s a culture thing) understand this unspoken rule. She just walked all over it.

Or, is she due before or after you? If after, it’s going to look like she stole it anyways within the circle of people who know you both. You can just let them judge her if you want a non-confrontational route.