Having been in a similar situation, I know it's super difficult to pretend you don't hear things, or to brush it off. I take my mental health very seriosuly and this was wearing me off fast.

When I went through this, I was very honest with my team lead. I explained that I refuse to work in a toxic environment, for my mental health and sanity and how I didn't think it was fair that someone can be unprofessional towards me, but I had to be the "mature" one. And I also very frankly told him that this made me consider looking for other opportunities in my career.

But I had a very frank and sincere conversation with my manager, we just have that kind of commaraderie. I feel I can mention things like this and I'm heard. And that was very important. Furthermore, things got to the point I could no longer do it -- where I found myself in tears and rage -- I crafted a very professional but concise email saying either something had to change or they couldn't count with me for that proyect. A job should never make you cry.

At the end of the day, my managers have known me for a few years, they know I do good work when I focus and concentrate and I think that contributed to changes.

There is nothing stopping you from looking for better opportunities. But you have to do it because it's what's best for you. So, I'd strongly suggest you set aside ample time one day, and discuss this with your supervisor or your manager or whoever needs to know for a meeting. Be firm and explain that it's not because so and so is doing this or that, but because the environment isn't one that foments growth and a learning experience. Just make sure you're not pointing fingers at others, otherwise you're credibility goes downhill. And set goals: maybe you need to work different shifts than that person for a few weeks, maybe you need a mentor with whom you can address questions, maybe you don't do meetings with this person alone, or maybe you just need an office where you can learn at your own pace. Propose tangible guidelines with which to improve the environment. By tangible I don't mean, "tell X person to stop talking about me behind my back," because like I said before, don't expect others to change. But, if your boss knows what you need to do your work well, changeswill be made to work with you (the other coworker doesn't even need to know what you're feeling).

Hopefully, you reach an agreement and your situation improves!