Your weight is the biggest problem but you probably know this and is probably why you are cycling - no?
But - the front area of your body just above the problem area is adding to the pressure so try riding more upright for now until the belly goes. You might want to try standing on the pedals briefly/occasionally to allow blood to flow more easily.and make sure your shorts fit properly, companies like Assos design their shorts to allow for the bunching up that naturally occurs 'down there' in a bent over position.