I don't have any idea about it. <--I have no idea what it might mean.
The floodgates open to all that has been going on behind your back - there is not a truer saying than the wife is always the last to know.
Floodgates are opened to let all the water out when there is too much water in dams or lakes for example..
In this case it means that the wife is getting to know all what went on behind her back as everybody is now telling, or she is getting to know through all the procedure even being told by her own husband. So all the information is now available which in this case is probably not such a good thing to happen.
In Spain we say:
Ojo que no ve corazón que no siente= Eye that does not see, heart that is not hurt. ;)