AITAH for stepping back from a group of cousins after realizing they only invite me when they need free labor?

My cousins love planning events but they never organize anything themselves. Every time they want a birthday celebration or a reunion they message me asking if I can handle decorations cooking and setting everything up. They say I am the creative one so it makes sense. I thought we were bonding so I always agreed. I only noticed the pattern when they had a small trip and everyone was invited except me. Later they claimed they forgot. The next month they asked if I could help set up another family event. I told them I felt unappreciated and tired of being called only when work needed to be done. They laughed it off and said that was my role within the family group. That made me feel like a tool instead of a relative. Itold them I would not be taking on any more tasks unless we shared the responsibilities. Now they say I am overreacting and ruining the funAITAH?