Mother in law troubles

Until the 1st of July, my boyfriends mom is living with us. A while ago, my boyfriend and I were thinking about getting engaged, but we got in a huge fight and decided to delay it. Well, we're talking about getting engaged again and she was evesdropping on our conversation and burst in and said "he would have proposed to you earlier but you screwed up so you missed you chance." And she is constantly getting in our business and bossing us aroung, I try to talk to my boyfriend but he doesnt do anything. What should i do? Do i have the right to be mad?