This is my first time posting and I'm quite apprehensive actually but I desperately need some advice. This may be a long post as this is a long story.
I returned to work this past Monday (14/10/2019) after having a few months off with my little boy. Upon my arrival my manager pulled me into her office to discuss my job and whilst doing this she brought up a few issues I've had with a colleague. See, as soon as I walked through the door on my first day she decided she didn't like me and would consistently make remarks about me or speak about me behind my back. It got a lot worse when I revealed my pregnancy, I knew she was desperate to get pregnant and due to our issues I waited as long as possible and requested that my manager told her about it individually before I told everyone else in a meeting as I didn't think she'd take it well coming from just me, I figured that way she wouldn't feel embarrassed being upset if it was just her and my manager. But after everyone was told she was calling me fat behind my back (Which I found hilarious as I was a size 12 up until the last month of my pregnancy where I ballooned) laughing at me and one day she almost knocked me over (Yeah whilst I was 7 months pregnant) because she was bouncing her way through a door and she didn't even acknowledge me. However whilst I was speaking to my manager on Monday she mentioned that this girl had been calling me ignorant while I've been off and had told my manager that I had ignored her multiple times when she'd tried to speak to me which was simply not true and I told my manager this but I was strongly under the impression she didn't believe me at all. Anyway, my manager brought this girl into the office and told us both to basically stop being so petty which I would have been fine with, we both agreed and moved on.
Until the next day, I walked into the kitchen at work to make my morning coffee and overheard her calling me again and when I walked into the room she told another of my colleagues to shut up by coughing at her. I was humiliated but still I didn't want to get anyone in trouble so I said nothing. This morning (Friday) everyone was planning the Christmas party at work, they're all planning a big weekend away with everyone from our depot and every time I tried to say I was up for going this girl spoke over me. Everyone was asking her if she was going and they all completely ignored my existence including one of my best work friends.
I feel bullied, I feel invisible and I feel like just quitting my job because it's been 5 days and it's making me miserable. I've suffered with horrendous Post Natal Depression to the point where I was actively not looking after my own well being (walking into the road without looking because I wasn't bothered about being hit that sort of thing) and this is making it so much more difficult and I have no idea what to do. My supervisor is the only one in the office who agrees that this girl isn't nice to me at all and it's not my fault but even she can't say anything until I say so. I'd feel so much differently about it if I'd actually done something to her. I've been bullied so much throughout my life from other students at school to teachers in school and college to girls who say they're friends with me I just never thought I'd have to feel like this in my 20's when I'm a mother. I'm just needing some advice on what to do because I'm feeling very, very low again.