Am I right in thinking this is rude behaviour?

My mum’s boyfriend keeps interrupting me when I stare an opinion or say something. He interrupts either to say that what I’m saying is stupid or wrong, and does it very dismissively.

eg.) I’ll say “I think war is wrong, and this is because..” and before I can finish my sentence he interrupts with “nah nah nah. I’ll stop you right there. You’re wrong about that. That is a stupid point that makes no sense.”

am I wrong in finding This really rude? He doesn’t even listen to what I have to say usually. And he gives me this condescending look.

Am I right in thinking this is rude behaviour?
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