E: solved, it is 2010's Good Neighbours, all credit to u/the_long_halloween
I've been trying to find this movie for a while now and I can only remember a few probably out of order snippets of it. A young woman living in an apartment with her cat, her older woman neighbor in the building is antagonistic towards her and iirc kills her cat when it escapes. There's also a male neighbor who was trying to get with her and gifts her a new cat, there's an establishing shot zooming in on the cat as it kneads the blanket. She finally sleeps with him but saves the condom in her freezer. Eventually she kills the older woman and uses the condom's contents to frame the man for the murder to presumably get him out of her life too. I'm almost positive it was on IFC a bit over a decade ago now but every time I've tried searching for it nothing really comes up.