Posts some photos my friend. I have snapped several tops. What I think is best is this:
Cut a piece of straw about an inch long.
Cut it down the middle so it can be opened.
Open the straw and place it around the part that is broken
If this doesn't hold it up alone then also add tape or garden wire (I prefer garden wire)
This should keep the cola upright and will make the stem stronger when it repairs.