What Should I Do?

I'm a 25 years old lady and I met my fiance(31 yrs) July last year and we are set to marry by January. We got talking and he told me the last time he had sex was June with his ex in her fiance's house.

The girl had her wedding in December. She was heavily pregnant and by march she gave birth to a baby boy. My fiance told me all this and being the curious person that I am I had to search for her on Facebook and I added her. I am always checking out her pictures and all just out of curiosity.




She puts up a picture of that baby monthly which shows his growth but I had to check out the pics today and I immediately saw my fiance's carbon copy. Gosh the baby looks so much like him. My bf has a particular shape of head and this baby has it too. His mouth, nose and all the facial features are the same with my bf. Putting two and two together there's every evidence that this baby is my fiance's.

Right now I'm confused. I feel hurt. My conscience won't let me be. I feel the urge to let the lady know dat I know and I also pity her hubby taking care of a child that is not his. The baby doesn't even look a bit like him. Once you see my bf and the baby, you will think he vomited him.

I'm just too confused right now. I don't know what to do. I love this guy very much and I want to marry him but my heart is really shattered by all what I saw. I'm sure this girl too knows that the baby is my fiance's. Whats the solution now??