Nihilism and post-breakup stress (I'm new so sorry if this isn't where i should be posting this)

I've been studying neurology and psychology and adjacent fields for maybe 1 or 2 years now? And its made me nihilistic and deterministic (basically i don't think free will exists)
It wasn't an issue for quite some time and I even got into my first relationship at some point with someone I really trusted and she was pretty much the only person i trusted enough to be completely vulnerable around

But recently the relationship ended because our interests didn't quite align (we do both have passions in psychology but recently its become something pretty depressing for her and she doesn't quite count it as a hobby, her hobbies are more like reading fiction and playing games whereas I like doing math and reading non-fiction) and at some point she started forcing herself to talk in a way that wasn't really her and it got really stressful for her and after maybe one month of discussions (which was stressful enough) she decided to end it (twice because after the first she wanted to discuss a little more because she thought there might be hope but nevermind there wasn't any for her so in the end we broke up)

So now my emotional support structure is kinda gone (I do have some close friends but I'm not close enough to them to be vulnerable around them like I was with her) and whenever I get sad when I get reminded of her the nihilism jumps in and makes the entire situation worse (so it's kinda like an oppurtunistic pathogen, only becoming harmful when I encountered a major stressor) and all my passions are in neurology or psychology and sometimes when I think about them I get into a depressive mood and I feel for a brief period that this interest of mine and my nihilistic deterministic beliefs is what contributed to the breakup and as a result I feel very down for quite a while (and sometimes its even caused some panic attack like symptoms like feelings of being choked)

And I have some friends that are nihilistic too and they're pretty down a lot of the time and I can't say my previous neurology/nihilistic rants didn't contribute to their now nihilistic belief and I feel a little guilty about that too

I don't know I've just become pretty vulnerable to nihilism and the depressive thoughts it can cause and I'm pretty worried my motivation is at an all time low and I can't seem to concentrate well on important stuff either

I should mention now that I don't think what i experience qualifies clinically as depression (i've checked against stuff like dsm-5 or whatever and no its not completely obstructing my life as of now) so I'm really sorry if that means I shouldn't post this here

And I know this entire post is kinda messy but I hope its articulate enough to read through