S.A.
I am in the same situation! I also speak two languages, and my husband only speaks english.
I believe it IS recommended that you only speak the other language, and your husband speak english to him (that was what my pediatrician told us to do anyways).
I have a friend who does it that way, and her children (2 and 4) are very "bilingual" and know WHEN to use french, when to use english, etc. They mix up some words sometimes, but for the most part they do pretty good.
I also have a friend who is Russian, her husband is french, and together they speak english. Their son (who is now 4) is perfectly trilingual!
Personally, I find it "awkward" since my husband doesn't know what I am telling our daughter, and same with all my friends who don't speak french. So I try (as much as possible) to speak/read to her in french when it's just the two of us. But I kind of regret it now, I wish I would of started when she was born speaking ONLY french to her all the time because I see how well it worked for all my friends who do it (and with my mom did it with me, and I was perfectly fluent in both french and englsih from 2yrs old), and now my daughter can only say a handful of things in french, but speaks 8-10 word sentences in englsih.. oh well, as long as she picks it up enough to hold a conversation I'll be happy I guess :)
Good luck!