I'm going to tell my male cousin that I had a massive crush on him growing up in front of his very insecure wife
Do you think that's a good idea telling your cousin that?
I think he will be very flattered and happy for me, we're very close to each other even we're cousins
That is the last thing you want to do. Find someone and invest all your energy in it, instead of giving it to your cousin.
Why? I like the attention and confidence boost from my cousin.
You shouldn't be trying to have a relationship with your cousin. Especially since he is married. Find someboyd else.