can anyone recomend a yaoi manga that will break your heart but will have a happy ending? ...

http://www.mangago.zone/read-manga/itou_san_kuraka_sui/

http://www.mangago.zone/read-manga/500_nen_no_itonami/

First Yaoi to EVER break my heart: http://www.mangago.zone/read-manga/kasa_no_shita_futari/
This manga is so beautiful and pure hearted, I just, the ending you will cry for days- I just can't even, I'm still crying: http://www.mangago.zone/read-manga/jigoku_meguri/
THESE ALL HAVE HAPPY ENDINGS
Though this one might leave you a bit unsatisfied: http://www.mangago.zone/read-manga/under_grand_hotel/ I cried for days. There's a one shot extra ending chapter which is really good and there's a spin off series which I am still crying over called Kiss & Kill.

I 2nd Ichiro's suggestion on "500-nen no itonami". And you might like this one too if you like tear jerkers with happy ending - http://www.mangago.zone/read-manga/thank_you_my_god/

This made me cry~
http://www.mangago.zone/read-manga/itou_san_kuraka_sui/

And maybe this one, although the ending is debatable
http://www.mangago.zone/read-manga/because_of_you/