In need of relationship advice?

my best friend of about 4 years, matt, just got a girlfriend. I have been in love with him for the longest time, but some how i became the person he comes to with relationship advice. I dont know how to tell him how i feel, without it recking our relationship. We tell each other everything and i honestly love him. I know i should be happy for him but i can't help feeling hurt and sad that it's not him and i together. What should I do?