How to avoid confusion from teaching bilingual to kid? I'm afraid it will affect my kid's abillity to speak.

I dont think they'll be confused. Other people, maybe. If you speak language a and c, your husband language a and b, and grew up in environment with language c. Pretty sure LO will pick up on everything. I've got lots of bilingual even more - friends and families who spoke at least 3,4 languages. They're doing just fine.