Quitting heroin while pregnant

I'm 5 months pregnant and have been using heroin through out my whole pregnancy unknowingly. I didn't know I was pregnant. I want to quit cold turkey and I have but lately I have been obsessed with the whole situation I've been reading online non stop about fetal withdraw I just want to know what are my chances of miscarrying now that I've stopped I know quitting was the best thing but will quitting cold turkey cause too much stress on the baby? I feel fine and go for another ultrasound in a couple of days to find out the sex. I'm just too scared to get excited about the baby and very confused I'm worried that quitting is going to cause more harm my biggest fear is losing the baby. Has anyone quit cold turkey this far into a pregnancy and still had a healthy baby? Has anyone actually experienced a miscarriage due to withdraw ? This may not be the best decision but I am trying to avoid having to tell my doctor considering I am clean now. I just want to know the baby will make it. I'm afraid if I tell my doctor they will put me on methadone even though I am clean and I've witnessed methadone withdraw first hand and I do not want to go that route either unless it is absolutely necessary.