Have your friends changed since you got engaged?!

I'm not usually one to jump to the, "she's jealous" explanation, but given that she's telling people she's "angry with you" because she should have gotten engaged first, it definitely seems to apply in this case. Obviously, she's "angry" about something that has absolutely NOTHING to do with you. I'd probably give her some space and see if she comes to her senses. When around her, I'd try to be sensitive and not talk about wedding stuff with her, since that's clearly a sore spot. Hopefully, she'll come to terms with her feelings and recognize that there's no connection between you and what she's upset about. Good luck! Enjoy the love and support of your other friends, and try to minimize her drama (including talking about it with others).

I hate saying this, but with a lot of women it's a competition. I don't know why. A friend of mine (not a close friend like yours) knew her boyfriend was going to propose around the same time as mine, and every day she checked in like "has it happened yet?" because it hadn't happened for her and she wanted to make sure that it didn't happen for me. Annoying, but whatever. Then came the competition for wedding venues, and dates, and colors, mind you, NONE of these things I was concerned about, but it's very frustrating when you have a happy moment in your life and it's being made into a game.
OP, I totally understand your feelings of frustration but she's not going to get over it. A sincere conversation about how you would appreciate her support might make you feel better, but in the long run, people don't change their behavior when they're blinded by their desire for an engagement. Speaking from experience. You seem to have a great BFF and other people to support you, so focus on all of their love and encouragement. All the best

I sort of had a similar situation. My FH and I had been dating for just over a year when he popped the question, but we had bought a house together and lived together for a while as well. When he proposed to me my cousin was happy for us but she acted strange around our family and friends. Years ago in college my cousin would say to me how she assumed she'd be the first to get married because of her relationship status and while it may have been a passing comment its one that always stuck out to me. Fast forward to our engagement, another cousin had told me that she was going around making comments about how she doesn't have a ring on her finger yet blah blah. She and her then boyfriend had been dating for 6ish years. I think it bothered her that they had been dating for so long without a proposal when FH and I moved things along pretty quickly with buying a house and getting engaged. She never outwardly was rude to me, or ignored me, but I heard through the grapevine how she acted. They got engaged VERY shortly after we did, and his proposal seemed rushed and ill planned but that may have had nothing to do with anything. She set her wedding date for 2 months before mine, they got married last weekend. We are each others bridesmaids and there was never any actual tension but there was enough weirdness for myself and my family to raise an eyebrow a few times. Everything worked out in the end. Either way, I'm sorry she has been acting this way towards you, you did absolutely nothing wrong and your engagement doesn't affect her at all!