My (24F) husbands (33M) brother(28M) called me a golddigger because I have BPD and NPD what do I do?

Tldr; we were visiting his family and when I was alone he confronted me and called me a gold digger and accused my son of not being my husbands.

While my husband was off with his parents and sister I was alone with his brother for a while. I wasn’t into the activity as they were hiking and I’m 7 months pregnant and lazy so that’s not for me.

I was lounging around on my phone and relaxing when his brother came up and asked me questions about my mental health and told me that he was already suspicious of me but those diagnosis were the final straw. He then said I wasn’t a good person and a golddigger who didn’t love my husband and was using him for his money. That isn’t true and I said as much. I told him he was jelous of us as he’s still single and told him to stop hating us for being in a healthy relationship.

He then called me vain and basically told me he thought I was too attractive to be in love with my husband and that I must have another man on the side and that my son most likely isn’t my husband’s. I was shocked and walked off and he called after me that I didn’t deny it. I find my husband attractive and I’m confused at why he said that because my husband is a very good looking man. Maybe it’s because he’s older than me but I’m into older guys anyway.

He then told my husband that I hadn’t denied his accusations. My husband pulled me aside and told me saying he thought it was out of order what his brother said but asked why I didn’t deny. I think his brother didn’t tell him the full story but now my husband keeps mentioning it even though I reassure him constantly.