Looking for advice on coping with a situation

Hi there everyone,

I was researching ways to cope with a couple of situations that I've had with someone in particular and stumbled across this subreddit. It all started back when I first got with my boyfriend in January. My boyfriend's friend seemed to have a few little issues around our relationship. He thinks I'm the reason my boyfriend doesn't talk to my ex boyfriend but that is not true in the slightest, I've been called controlling and sensitive behind my back (the silly man talked about me to my best friend) and he just keeps trying to one up me, especially in front of my boyfriend.

The final straw was this. My friends, my boyfriend and I went out for a nice little dinner at the local Wetherspoons. I already wasn't feeling great because I struggle a lot with my Autism. This was plain as day on my face as I was not masking and was mostly like ':-|' the whole evening. I saw someone that deadnamed me because I wasn't attracted to him a few years ago so that already set me off. I was giving my boyfriend a tarot card reading as I practice Paganism and he asked how it worked. I was explaining that a lot of it is to do with the subconscious mind and that kind of science area. I want you to bare in mind that I was turned, talking to my boyfriend and not talking to anybody else. We were having our own conversation.

Out of nowhere, his friend pops up, deciding to join in the conversation. 'I don't think you know what science is. You're wrong'. All of these sorts of phrases were directed at me. Now, under normal circumstances, this could've been perceived as an ordinary conversation. But he knew that I was struggling at the moment in time and still he wanted to one up me. I've researched thoroughly on the subject as I wanted to make sure Paganism was the right label for me. I know what I'm talking about with this. I tried explaining what I was talking about to him and he just kept interrupting me. I ended up having the leave because I was being told I was wrong about something that I know I was right about (I wrote an essay on it the next day with evidence to back it up).

I found out from my best friend that he told everyone 'you know how they get. They're sensitive about things' after I had left. I'm not sensitive if I'm explaining something and you tell me I'm wrong.

I just want some advice I suppose on how to get over him doing me wrong all the time. I feel like I can't be around him because I'll just get so annoyed and overwhelmed. I want to learn how to not care about him and his presence. It's also important to bare in mind that this is a 22 year old WHITE man who still uses the n word, is still friends with someone who SA'd me and told me my experiences weren't what they were because he 'asked his friends'. My boyfriend and our other friend have both agreed that this isn't okay. I hope someone can help me understand how to ignore these negative feelings.