I can't add more to what has already been said, Toy_K. Except maybe, to please take it slow.
When your other half seems to cultivate a bulge in his pants when reading some BDSM stories, that is indeed positive.
Best thing is to first establish what exactly it is that exites your other half in the things he read while tenting his trousers, and maybe go from there.
A lot of people tend to cultivate fantasies, but are so afraid of xperimenting with those fantasies in the real world, in their relationship. Partly because maybe they are ashemed, or maybe because they are afraid that their partner will regard them as freaks.
So, when speaking openly about your desires, Toy_K, always lay the emphasis on your mutual love.
Visit some online stuff that handles about the psychological aspects of BDSM, or Sado-Masochism, to show your husband that having such feelings is pretty common. That's to take away the 'freak' aspect.
And, Like I said, take it slow. Be patient, and ask the same of your boyfriend. Rushing things can drive people apart.
I truly hope things will end up going smoothly, for the both of you.
What I wrote ain't much, but maybe it helped a bit
JJ