Overcoming Drug Addiction with No Help

Hello everyone. Gonna try to make this long story short and try to explain myself cohesively. I am in my 30s. Have an AMAZING child who is in Gifted and Talented in school and is the type of kid anyone enjoys having around. Such a good kid. I have an amazing fiance who treats my son more like a father and teaches him more etc than his real dad. I am a graphic designer. Been with the same decent company for 10 years. And.... I'm addicted to meth. I started doing it and other drugs in my teens. Did all kinds of drugs and drinking til I got pregnant at the age of 27. Stopped everything of course but about 1 year after he was born his dad and I did meth off and on til we split up. Moved in with family and my mom did it so we would do it weekly or so. I eventually got to where I am now. On it almost every day. I hate myself for what I am doing to my body just hoping I don't have some kinda heart failure or anything and live long enough to see my kid grow. I don't feel horrible and I look perfectly normal. No one suspects a thing. Not even my live in fiance who doesn't do any drugs and barely even drinks at all. I of course can hold down my job just fine and my son is so happy and healthy. I'm always full of energy and fun to be around most of the time. I do get down here n there and sleepy or PMSing like anyone else. But I don't show any of the signs of a long term drug addict. I honestly just want to stop for my son. Want to be here for him alive and not in Jail. Would die if something happened to him. And I dont know who would take care of him that I fully trust and that could if something were to happen to me other than my dude. But I haven't talked to him about that really. He just knows I am concerned about it. I try starting on a friday with not doing anything and going the whole weekend. No horrible side effects of withdraw that I can tell aside from just being SOOO sleepy. I have no health insurance. Cant at all afford to take off work for rehab and couldn't afford treatment with no insurance. Make too much for gov health care and dont make enough for even an obamacare plan. Have no one to talk to for support. Only ppl who know I do this is ppl who do it too. I wanna tell my fiance and use his support and just his knowledge of my situation to help me thru but I honestly dont know how he would react. Im afraid he would leave. Idk. I cant loose him. Or my kid. Or my job... When I go to work fully sober I cannot concentrate and sometimes just flat cant stay awake. So Im now just doing some daily to make it thru the day. Idk how to quit when I cant get any help and have no one to talk to