I'm so scared!! 😭

I'm currently 18 weeks pregnant, littlr to no cramping and no bleeding but i can't help wondering if my little one is in there growing, safe and sound.. how do I know he is? I know this is a stupid question but I can't help feeling this way and it doesn't help that I still smoke cigarettes and my fiancé and I have constantly been fighting.. and tonight he told me if something happens, he's going to blame me and tell everyone it's my fault.. He's always on me about the smoking so I don't need everyone and their uncle making feel worse than what I already do.. I'm trying to quit, but it's been really difficult for me. I just want to know my baby is alive and well in there. I feel ridiculous and scared to death.. 😭