he has certainly done a number on you. No, you don't deserve seven straight days of silent treatment just because you raised a concern about his sister.
Read this article from The Atlantic if you can. Your husband wants to inflict pain on you. 7 days not speaking isn't sulking - it is abuse. I think you would be far happier elsewhere OP.
Whatever You Do, Don’t Do the Silent Treatment
It can ruin your relationships.
By Arthur C. Brooks
Life for a 19th-century sailor was hard: Months at sea were accompanied by constant danger and deprivation. To make matters worse, mariners saw the same few people all day, every day, in a radically confined space where they were expected to get along and look after one another. On a long voyage, one obnoxious person could make life utterly miserable for everyone.
So sailors used a tried technique to deal with an offender: the silent treatment. They would ignore him completely for weeks on end. That might sound like an innocuous action to you, but in truth, it was far from it. The silent treatment was, according to the writer Otis Ferguson in 1944, “a process so effective in the monotony of ship’s life as to make strong men weep.”
Of course, the silent treatment is a technique used not only by sailors. It can be encountered anytime, anywhere, from home to work. You have almost certainly experienced some form of it. Being subjected to the silent treatment is a lament I commonly hear from others, on whom it is imposed by romantic partners, parents, friends, colleagues.
Long-married couples will go for days without speaking. A person will give their oldest friend the cold shoulder. I knew a father who refused to speak with his daughter for 30 years. Silent-treatment inflictors do it because, as the sailors discovered, it was devastatingly effective in imposing pain on the recipient. So much pain, in fact, that it can leave a person scarred and a relationship in ruins.