You aren't alone my friend... there are a TON of people out there who have experienced what you are going through... maybe consider it a growing pain. You are an independent person yes, but you are not alone... that independence, when moving from a mono type relationship to a poly one is glaringly obvious in the early days it seems, but it is not necessarily a bad thing, just uncomfortable and one needs to adjust to it. It feels uncomfortable because we are not used to it in monogamy. We are used to being more entwined and merged together... poly offers a separateness that means more personal involvement with ourselves while loving and relating to others... its hard to explain, but most definitely feels like being a lone when you aren't used to that feeling. You and her are likely still good, just changing into something different, there is bound to be tears with that. Keep at it. It's okay to let her know you are struggling. It's normal and likely it will help her empathize and feel close to you. I admire you for sharing your tears here... to me that is the stuff of great men when they can admit to crying... good on you!