I Need Advice! Follow My Heart Or Spare His?

Hi. So today I came to the startling realization I had fallen hard for my friend, who we'll just call J. J and I reconnected after around 8 years and Immediately after seeing pictures of me on my facebook and what not, he confessed to having feelings for me. I in turn told him I had a boyfriend, making sure he got the message by sending pictures. However, daily he's been flirting with me. He's really sweet and honestly kinda hot. And every time he flirts with me I get all Fangirly.

Then there's my boyfriend... who we'll just call T. T and I started out as best friends before we wound up dating. So I know the ins and outs of his life and I want him to be happy. I seem to be the one thing that gives him that happiness, as self centered as that sounds. His family treats him like garbage and all his so called "friends" have been pushing him away and ignoring him. And he complains to me about it every day, and while I feel bad for him, it's started to stress me out ALOT. He complains far too often and having to calm him down all the time has gotten to be a pain.

J asked me out before he found out I had a boyfriend, and I've been seriously considering the offer. T is deep in depression and without me I'm scared he will kill himself, so I'm not sure if there's really any choice to be made here.

What do you think I should do?

Be selfish and think about yourself. You aren't living a life to make someone else happy.