Polyamory

My husband is poly and I’m mono but we’ve decided to open our relationship to include another woman for a closed triad (I’ve been researching a ton on this) we haven’t met anyone yet but a part of me feels like this is a huge mistake I’m having difficulty with knowing one day he’ll tell another woman he loves her and seeing him having sex with her it excites me and breaks my heart at the same time but I want my husband to be happy but I worry about being disowned by my family for being poly and bisexual and how it will affect my children I have 2 boys I’d prefer them not to know because small children always tell the truth which is what I want to teach them but I don’t want my family to know