Possibly pregnant

My husband and I have been TTC and now I may be pregnant I go in Monday to find out. I'm super excited and my husbands excited but also super neverous. He worries about everything all the time even stuff that won't effect us now. I think he's sorta over reacting a little. I know he will be over joyed once he sees the baby and things progress with everything if I am pregnant. If I am how should I tell him without a complete freak out happening? I want to tell him in the best way possible without him over thinking anything or feeling overwhelmed. He was the one who told me he wanted another child and wanted to try for a girl to add to our family. He loves going and looking and stuff and talking with me about names. But he gets in his own head about things and what's ifs. I've seen some cute ideas which I know he'd like but I'm not sure how to go about this fully. I haven't told him about my appointment Monday because I don't want him stressing till then. Which I already feel guilty about because I never hide stuff  from him.