My coworker vents about work to me nonstop and wants me to pick sides even though I'm new. What is the best way to remove myself from this?

when I first started 6 months ago she invited me to hangout outside of work and I was excited to make a friend but then it quickly turned into a venting session which I didn't know how to get out of in the moment. I should have shut it down immediately but she talked over me a lot. since then she has tried to vent about colleagues and work and I've told her I didn't feel comfortable with this and she continues to vent within ear shot of other colleagues. when my friend died a couple months ago and I was grieving/still showing up for work she continued to talk about herself and vent.

when I told her I felt uncomfortable with this last week she told me I had become awkward and that I act differently at work. she seemed upset I wouldn't take her side. I don't know why she felt so comfortable telling me everything but I don't want to be caught in work place drama. I feel that she's told me way too much and other colleagues seem uncomfortable around her as well. she's leaving our company soon apparently and I want to try to stay as neutral as possible until then. I feel like I gave too much leeway at the beginning of our interactions so I don't know how to correct it. I'm scared she will reveal things I've said in passing when I initially tried to be sympathetic to her and get me in trouble at work. I know I made a mistake.