My Elder Brother's Fiancée Is In seriously in love With Me

My elder brother's Fiancée is dying for me and my only brother who trusted me so much never notice it.Honestly, i don't know what to do.....

All this started when i celebrated my birthday last year and my elder brother funded everything such as drinks,foods etc, except the cake and the party house decoration which was funded by his fiancee, She even bought me a 'Rolex stone watch' as a birthday gift right before my brother.

I never knew that she had feelings for me then, until one fateful morning, when she blew it open by sending me 'morning love texts' confessing that she loves me & will do anything to make me happy.

First time i saw the text, i thought it was a mistake, that she wanted to send it to my bro but when i call to confirm, she told me that the text was for me. At first i couldn't say anything, i was speechless, never believed it until when i met her one on one in my bro absent that she make it clearer to me that she was madly in love with me at the process of the confrontation, the discussion even ended it up with a hot kiss.

Honestly, my brother's fiancee is very pretty and sexy that no man can resist her easily but my bro who trusted me so much never noticed this....... what should i do? Should i make this known to my bro or should i keep it secret & enjoy her ? Pls am confused now, i seriously need your advise!