Help ! I'm falling in love with my best friend

I met this really great guy at work and he's since become my best friend. We get on so well, can talk for ages and thoroughly enjoy each others company. Lately we've been developing stronger feelings for each other but neither of us will pursue those because he is already married, and we do not wish to do anything immoral. I feel so bad because this is the first time in my life a really great guy has been interested in me - I've never had a boyfriend before.
There's nothing wrong with me, I just seem to be unlucky in relationships - always falling for the wrong guy, or getting taken advantage of by so called 'friends', or simply miss out due to bad timing.

Is it possible to get rid of these feelings and still stay friends with him?

He is the first person in my entire life who has been a genuine friend to me and I don't want to lose that.

Stick to your morals and don't be a housewrecker, just put yourself in his S.O's shoes.

Just keep it laidback and cool and you can easily still be great friends with him.

It sounds like you are infatuated. Take some time off and put a bit of distance between you and him, your feelings should die down. Sometimes they don't. If that happens you may need to make a choice of whether to continue being friends with him or continue holding your distance.

I was infatuated with a girl from work once before, I did the above and it helped me get a better perspective on our friendship. Stepping back a bit showed that she is actually not right for me, we are still friends but all feelings I had for her have disappeared.