Should I still bake the cake?

Me and my boyfriend broke up last night and I told him to not even bother texting me later apologizing when the regret settles in. He always treats me poorly and when I confront him it turns into an argument and I finally broke it off after dealing with this same situation multiple times. His mother 3 days ago asked me to bake her other sons (ex’s brother) birthday cake because everyone loved the cake I had baked my boyfriend for his birthday a couple of weeks ago. His birthday is this Saturday and I planned to start the cake Friday. I haven’t talked to my ex the whole day but this question has been lingering in my head. I already bought the candles and ingredients. I’m not sure if my ex is even going to tell his mom we broke up and if she is still expecting me to bring the cake. I don’t have her contact information so I’m not sure what to do.