The title pretty much is the main question, so feel free to not read the rest if you don't want to. I'm confused about whether things can cause splitting or if it it supposed to just occur at random times. I'll elaborate a little bit in case it helps clear it up since I haven't seen a question like this here before. 

I definitely experience something that I consider splitting on people that I am close with, where I go from loving them to hating them, not wanting to be around them, all of the things that people mention when they talk about splitting and black and white thinking. I've been tracking my moods more closely recently, and I realized that this splitting behavior occurs almost exclusively when I am experiencing external stress or anxiety. For example, I had a huge presentation for school on Monday (determines whether I can or can't graduate, so very very important), and all day on Sunday I was extremely anxious about it. I ended up splitting on everyone around me (or what I think is splitting, basically hating everyone, devaluing them, causing arguments, and being incredibly irritable) all day long. 

My main questions are: Would that still be considered splitting if it's linked to an external anxiety-causing source, or is it just irritability associated with the anxiety? Does anyone else experience more irritability, mood swings, or splitting when they are experiencing extreme anxiety? Is this still considered a symptom of BPD or is it just purely anxiety? 

I'm just confused and it helps me to be able to dissect my feelings and where they are coming from to help make sense of them, but I'm hung up on whether it's anxiety, splitting, or both.