She posted a sweet video with pictures of Avicii and her and her son.
There were more pictures, but since her instagram got deleted I can't link and ain't nobody got time for that.
After this post, she posted a letter "for Tim" where she posted a bunch of personal things, such as how she got her period blood all over his bed.
She then posted a video of her son crying for Tim, at this point Tim's (Avicii) sister had had enough and sent her DMs and posted on the video, saying it was disturbing and asked Tereza to please delete it, she also posted a comment asking Tereza to delete her posts, as they were exes, and hadn't been dating for a while.
Tereza deleted his sisters comments, but ended up deleting the video after a few days. (Enlinda is Avicii's sister).
This made all the fans go crazy and post lots of mean comments, which made Tereza write a new letter, where she calls his fans sociopaths, tells them they can't call him Tim and something akin to "you are just jealous he was with me and not you".
Instagram took the letter down 3 times because of foul language.
She reposted it 4 times, the 4th time she compared instagram removing her post to modern day slavery and went on a huge rant against instagram. Instagram responded by deleting her account.
I can't find screencaps of everything, but basically she's a mess, and probably wasn't dating him at the time of his death, and the fans are a mess and commenting on her instagram that she was probably the reason he killed himself.
It should probably be noted, everybody else around Avicii/Tim posted short sweet msgs about how he's probably at peace and even that he wouldn't have liked long personal msgs.
Source & Google