To see something decomposing in your dream signifies the degradation of a situation or circumstance. Something in your life is falling apart - but remember, unhealthy things must fall aside in order for new and healthier things to enter your life.
[1]1. Emotional regeneration, renewal after difficult times.
2. A situation is in decline, degrading into difficulty.
3. A stagnant, possibly “rotten” attitude or situation that needs attention.
[2]