AITAH for asking my husband to stop funding my MIL and SIL’s lifestyle.

My husband (m38) and I (f36) have been married for six years now. My pay has always been double his, so I’ve been taking care of most of the household expenses like rent, insurance, and utilities, while he handles the groceries. I’ve asked him multiple times for the past few years about having a baby and buying a house, but he’s always made excuses, saying we don’t have enough money for either. So, I’ve been saving as much as I can and putting in extra effort at work to earn more.

Recently, I found out that he’s been buying a house for his sister (f36, not married) and paying the mortgage on it for the past couple of years. On top of that, he’s been funding their lifestyle and trips, even though his sister has a good salary and is working. I feel hurt because he lied to me about our financial situation. He made me believe that he couldn’t help us build a life together, while I’ve been managing everything—our expenses, trips, and even saving for a future home. I asked him to stop sending money to his sister, but he refuses to stop paying the mortgage.

What should I do?

Edit: We had a huge fight when I accidentally found out that his earning way more than what he told me and I even asked for a divorce. He started crying and said he was embarrassed to tell me the truth. Apparently, his father doesn’t have any money, and they’ve never owned a house. He wanted to buy a home for his mom. His sister took out the home loan, and so the house is under her name, even though he’s been paying the mortgage. I don’t understand why he would find this so embarrassing to hide it from me, his wife. He said he’ll start saving for our future home, but he insists on continuing to pay the mortgage because he doesn’t want to burden his sister. By the way, his sister (f36) isn’t married and is living with my MIL in the house he bought. We have separate accounts and so it was easy for him to lie about his salary and how much he could pitch in.