I'm glad I could be of help!

(My situation was extremely similar!) I also had known someone who was initially nice to me, but then started getting extremely jealous of anything I did. They also would intensely express how much they "loved" me (platonically), but I didn't realize until it was too late that it was nothing more than an unhealthy obsession

I tried to keep thinking back to that initial good impression they had, but I learned I cannot deal with someone who has two different personalities (one side nice/giving compliments, the other side angry/possessive)
So I definitely want to make sure you don't deal with the same thing! It can be really draining mentally/physically, so setting up boundaries will make sure to decide if they are a true friend who respects what you feel comfortable with