Selena Gomez Celebrates BF Benny Blanco's 36th Birthday, 'I Love You'

Selena Gomez went all mushy-gushy with a sizzling birthday shoutout on IG ... celebrating her BF Benny Blanco's 36th in style. The actress/singer didn't hold back one bit in her post, dropping the L-bomb and spilling all the deets about what makes…