I overheard my coworkers talking about my replacement? Should I trust Mika after that?

Why is my coworker constantly asking everything I do? Is she micromanaging me? ↗

My superior called us for a meeting and my coworkers reported me instead of meeting? ↗

One time on my duty Im just beside Mica and Mica was talking to Nico and I overheard them that Nika is coming back to apply again. I just looked at them and saw Mica was facing Niko. And I overhead Mika said to Niko pointing on my direction that Nika wanted to replace me on my job but my contract got renewed again. by the way me and Niko are not regular workers just job orders. And Nika used to work here she just got a baby and delivered the baby and after that she didn't come back and found a new replacement for her And by the way Nika is my old coworker she's very mean and very condescending based on 2 questions above. I remember her reporting me to the boss on my first month of work in a meeting like she did me dirty if you will read it. I just felt bad when I heard Mika talking behind my back about my replacement to Nico and also angry/annoyed that Nica is just waiting to replace me on my work for her to work again. Like she just really wants to get rid of me for her to get my position. by the way there's new position that is open and I heard Nika applied for that job and I instantly thought I wished "She never get hired becauses she's selfish" am I bad for thinking that? Also should I still trust Mika after talking about my replacement to Niko?
I overheard my coworkers talking about my replacement? Should I trust Mika after that?
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