AITA for not telling my MIL what actually happened to her cake?

I (f26) recently married my husband (m31) of 6 years. His mom and I aren't close at all, she doesn't like me but tries her best to be nice to me when she has to and I do the same in return. My husband and I live about 30 min away from his family but he visits them often without me knowing (I asked him to stop this and he won't, I've asked him to tell me and he won't so I had to install a car tracker to be sure). My husband got a 30 day out of state work assignment and I went to stay with my family for the month. When he got back I went back home. Apparently while I was away his mom got upset that I wouldn't let them in the house when my husband is away (I don't feel comfortable allowing his family in the house without me or my husband there) so she decided to play a "joke" on me. She dropped off a cake to the house that she asked my husband to tell me was from him. When I sliced the cake I found that it was filled with dog food, mud, and pee. Obviously I wasn't happy and it was disturbing so I threw it away and ignored it. She's going crazy thinking that I'm making a big deal out of a joke and wants to know what happened to the cake she gave me, I just told her that I ate it and thanked her. She asked if I shared it with anyone and I told her that I didn't. She asked if she could come over to our house (my husband and I live in the house that I grew up in. My dad passed away a few years ago and my mom passed away when I was young) and I said no but she's still trying. She's telling my husband that she needs to see my house (never been in it before) so she can plan her Christmas party that she wants to host at our house. She's already trying to plan out the decorations and while she's telling me all of this I can hear my husband agreeing to everything in the background. AITA for not telling her what really happened to the cake she brought over?