so many mixed emotions what should I do?

Jenna
Me and my SO was pregnant in Oct 2016 to triplets which ended in a missed miscarriage- it broke our hearts and even though my fiancé put on a brace face I know it tore him up inside. It would of been his first time being a dad - we started trying again Jan 17 and I have been dreaming of the day that we get a positive so I could tell him and see him so happy again - I am 12 DPO today and I haven't had any symptoms but for some reason I thought I would test and to my shock it was positive now has much as I am over the moon I am so scared all of a sudden I thought I would be screaming down the roof with the news to my SO but I am actually now scared to tell him invade it turns out to be a chemical pregnancy or miscarriage - how long do you think I should wait to tell him? I'm so confused with the emotions I am feeling x