How do I still have fun even though I don’t like her?

I work with this one girl who I don’t hate but I’m really not a huge fan of her. She’s very pessimistic and I’m very very close to another girl there my age. This rude coworker is a year and a half older than me and my close work friend. I’m really close to this friend like I said and there’s like sparks there between us romantically and everyone knows we’re close and sees that things are happening with us but things are still being worked out.
So this other coworker works in the back thank God but every once in a while she’ll come to where my friend and I work and say hi or something. She’s not a horrible person but she’s been really rude to me and others before. In the past she’s been extremely dismissive towards me and my lesbian crush which hurt my feelings and I talked to her about it one day at work and she apologized and said that she thinks I’m too attractive for my crush and that’s why she acted that way and we seemed to start fresh. She even sent me a text the next day saying being at work reminded her of our convo and she wanted me to always come to her if I felt upset and she’ll work on her delivery. I appreciated that and we moved forward. We’ve had deep convos but occasionally I just still feel on eggshells like she’s very critical and if I say the wrong thing she’ll judge me lol. She invited me to her bday and I didn’t make a big deal about getting her a gift because she’s never given me a gift for my bday or my graduation but I’m going because my close work friend who I mentioned is going lol and she gets along pretty great with our coworker. I’m going to go and try to have fun but I do feel like she treats my close work friend differently than she treats me. I got her some stuff as a gift but I texted her happy bday like an hour ago and she hasn’t responded which is fine but Ik she’s in close contact with my close work friend for stuff for the party. How do I get through this?
We’re all girls by the way lol.
How do I still have fun even though I don’t like her?
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