Fannie Mae Sold me a house that support beam is rotted and split. House is going to collapse. Atlanta GA

Fannie Mae sold me a home almost 5 years ago.  The home is only 13 years old.  Found that previous to me purchasing the home the house has been leaking sewage between the walls.  An engineer stated not only that leak but a leak from the flashing on the roof which is another leak that had made the support beam rot and split.  

My insurance will not cover the leak from the roof.  By the look of the beam, this leak has probably been going on since the construction.  So if this leak was before I purchased the home, that would make the house 8 years old which is definitely not my issue but no one wants to take responsibility and my house is literally standing by a thread.

I worked with the realtor Ashley Augustin and as a first time home buyer, I trusted him.  He is the one who brought in the inspector to inspect but I guess he never bothered to look at the structure. When I purchased the home the floor was warped. So that alone tells me this was going on before me.  Please help me!