To revel in my anti-Christmas sentiments

[2ndSopranosRule]

Staff Christmas thingie, happening as I type. I'm covering something I can't not cover, I've got stuff I want to do this lunchtime and I'm not going.

Plus, some of my colleagues have been absolutely awful to me this year (properly awful: I'm on antidepressants because of it) and I'm not spending a second of my free time with any of them.

Just come under a bit of pressure to show my face as I'm senior (nominally, although I'm not paid as such and they won't actually formalise it).

AIBU to actually do my job during this period, do whatever the hell I want over my lunch break and disappear for 20 minutes rather than engage in forced jollity?

If they have been horrible, no YANBU
If a few of them are reasonable, maybe next time do go to the Christmas get together but perhaps spend most time with those people? Anyway, this time round I don't blame you, just do what feels right for you

I didn't go last year either.

I've only been on the evening do once in nearly ten years (struggle with childcare mostly) and I'm pretty sure I've not actually been invited this year.

See, now I'm feeling very sad because I'm reminded of what a terrible time I've had work-wise .

Well you are a great employee,having been loyal to them for 10 years, so who cares what they think, don't give them a thought and enjoy your time and space catching up on shopping/having a quiet peaceful break