Right, im back.
I spent 2.5 years working for someone who spent their time undermining me, and making me feel worthless. It was awful, but they convinced me my worth was low.
I started applying for jobs, and the rejections were really tough - reinforcing the "fact" that I wasn't worthy.
It took one application to land on the desk of the right person, and a year on im transformed. My worth is valued. My skills are appreciated. And after 4 months, when the guy who recruited me handed in his notice, my colleagues persuaded me to stick my head above the parapit and express my interest. I got the promotion, and have just completed 6 monthsin that role, with an assessment paraphrased as "we haven't felt this comfortable with the running of the department in years, and it's amazing for us to know we don't need to keep checking in, because we are certain all is under control".
Please don't let your awful colleagues determine your worth and lower your self esteem. Get out, and find somewhere who lifts you up, not puts you down. But, hazard warning, you'll find a lot if frogs before you kiss your prince.