As others have said, “you look amazing…fucking bitch” to express that you look really good is very common - especially if you were closer friends at the time.
(What does your “heartbreak” have to do with this, other than possibly motivating a friend to compliment you?)
Commenting on your weight (during a heartbreak): trying to compliment you.
Fine if you don’t like it. Why did you wait until you were so pissed off by the comments that you “snapped at her” before saying anything though?
You were drunk with colleagues, they probably already knew. Why would she think this was private or sensitive information?
She’s comfortable discussing money, you’re not. That’s nothing to do with you. Have you told her you don’t want to talk about money? If not, how would she know to stop?
during my heartbreak, as aforementioned, I couldn’t eat. She kept shouting across the office how much ozempic she’s taking. It almost seemed like she was in a bid to compete
She’s talking about HER weight loss. It’s not about you.
I know she would berate me behind my back too
Has she done this, or do you just think that she ‘would’?
For what you’ve described, she sounds like she’s trying to be friendly but just isn’t your sort of person.
You come across as quite uptight, and as though want everyone to remember your “heartbreak” and tiptoe around you. You sound like you don’t have much patience for other people’s humour, and as though you expect people to understand your boundaries/preferences without ever having to state them (or at least saying nothing until you eventually “snap”).
I think it’s less friendly and more vindictive. I.e. I want what you have and I won’t compliment you. So I’ll create a burning insecurity within you, because I’ve never had therapy and project my unbalanced emotions
Suggesting she’s deliberately trying to cause insecurity in you because of “unbalanced emotions” is quite a reach. It’s a bit ‘main character’ to think everything she does/says is motivated by trying to upset you.
Tbh it sounds more like you’re insecure (you blame her for this) and imagining competition as a result, you don’t like her but you want to believe you're a "woman's woman" so you’re making that her ‘fault’, you know you’re not particularly easy to be around right now so you’re accusing her of being difficult, and your emotions are unstable because of recent heartbreak, so you’re projecting those unstable emotions onto her.
I'd say keep your distance because you don't like her, but stop with the character assassination because she's done nothing wrong.