My husband (45) has a 16 year old son from his first marriage. I’ve been in his life since he was 9 and we have two younger kids together. Stepson’s phone is completely smashed. His mum won’t buy him a new one and says it’s our turn. My husband wants us to split the cost of a new £600 phone. I said no. He already gets £150 a month from us for clothes, games, and pocket money. I think he should get a Saturday job and pay for at least half himself. My husband says I’m being unfair and “punishing” his son for having a useless mother. AIBU?