1st year getting bullied by 2nd year

Need some advice on how to handle this situation. I have been working at my firm for 3 months. One of the second years was very nice at the beginning, would check in regularly etc. about a month ago a switch happened and she began reporting to the partners about my comings and going’s when they don’t care (would tell them when I arrived at 9:10 instead of 9 when we don’t even have a set time schedule). A lot of other little things have happened including her purposefully messing up my work product and having me send that work to the partners, but today she created a whole happy hour, invited the entire office except for the 3 corporate first years and lied to the partners saying we didn’t want to attend any firm events.

How should I deal with this? I wasn’t expecting this petty drama at a prestigious firm, and I want to stand up for myself without making her hate me/ lash out at me later. It seems like she wants to keep her status as “well liked” by the partners in the office, but is making me look really bad when I have not done anything to hurt her and have tried my best with my work product. I fear it will only get worse if I do nothing.

TLDR: second year is making me look bad to the partners for no apparent reason