I want to tell my brother and SIL our good news BUT...

So I'm only 5 weeks pregnant and I want to tell my brother and sister in law, my parents already know as my mother and I are really close and I want to tell my SIL because I had a miscarriage a few moths ago and she was really there for me always checking on me and stopping by she still asks how things are going so ofcourse I want to tell her my happy news well my husband acted like he didn't want me to, we haven't told his family yet and he reminded me of that. well I have asked him several times when he wanted to let them know and he was vague and said I don't know ok well when you figure that out let me know; plus the last time we told his parents I came up with this really cute way and they just blew it off acted shocked said my husband shouldn't be able to have kids blah blah blah I was really upset they didn't act excited at all and I want positive vibes and people who I know will pray for a healthy pregnancy and I dont feel this way about his family they don't like me and I don't think they are to thrilled about us having a baby so I'm hesitant to tell them but when he's ready I will. I just don't know what to do I don't want to make him mad by telling my SIL before his parents but I also don't care about telling them this soon as his mother said don't people wait for the first ultrasound to tell people... I don't know what to do any advice!!