I started my bachelor thesis three weeks ago and I'm very struggling because of my supervisor.

He is extremely perfectionist, has mood swings and is very critical of my work. On the other hand, every time I hand something in or make a discovery, he's very happy and proud of me. He has high expectations of my work and says he's not so worried about me making progress, but his actions are not supporting this.

Today I had my first physical meeting with him. He already had rejected my project proposal twice the days before, both with very snarky emails that even got my partner angry.

He burned my work to the ground: my proposal was bad, I did not prepare myself good enough for his meeting and I had done nothing the last three weeks (which is absolutely not true since I've emailed him my results many times and each time he was very happy).

I'm a very perfectionist A-grade student myself and my rejection sensitivity dysphoria went through the roof. I started crying, which I absolutely hated. Then all of a sudden he started to soften: he approved my proposal, gave me actual feedback and told me not to worry so much.

I felt gaslit after this meeting and even though it's been 6 hours ago, I have a strong headache and don't much of an appetite. I've never felt so insecure about myself my whole time in academia.

How can I deal with him? It's a little too late to choose another subject and even though he is terrible sometimes, the data and the people I work with are very nice and provide good opportunities for after my studies. But I just feel like a failure and broken.