Sorry about your situation, Stein.
I can only share my own experience with you.
When I was young, I was TOO honest and got hurt a lot for blurting out my truths until I finally learned to LIE, like the other kids in the family, who all got off the hook when being naughty, by just lying about it! I soon noticed that their parents & my parents were more satisfied with our lies and didn't punish me (they were very abusive) if I told lies instead of embarrassing truths so, I became quite good at lying to my parents and everyone.
IT WORKED PERFECTLY & I was soon enjoying the perks all the other LYING kids were enjoying, so that was my code and policy from then on! Now I can see that the very bad and disrespectful relationship that my abusive and negligent parents created directly set me up to be a HUGE liar to avoid their blistering punishments. We were ALL the hapless VICTIMS of bad and inadequate parenting more than any other influence - including peer influences! Peer pressures all happened later in life after our parents had set us up to be so corrupt and dishonest!
As the child of inadequate parents (I'm 76 now) I'd tell you or any parent to get into some kind of therapy or counseling FOR YOURSELF to figure out where YOU WENT WRONG and begin working on you self from that point. My very inadequate parents COULD HAVE fixed all of the damages that they were doing to us kids if only they could have admitted that they were making mistakes and then asked us kids where they were going wrong. I could have easily told them that their biggest mistake was to push me away with their abusive punishments (and neglect) that broke the love, respect and loyal bond that I once had with them from day one. This "disconnect" just turned me into a LYING, SNEAKY, FEARFUL, ENEMY who did all kinds of sick things behind their menacing backs. They, not me, caused all of the sad and sick things I and my brother did by alienating us at an early age & losing the love and loyalty we once had for them. They needed to see a therapist or counselor but, in those days, that was UNHEARD OF! It should be obvious to anyone that, had our parents NOT alienated and forced us to go underground to do our thing, we would have come through as: HONEST, respectful, loving and LOYAL kids instead of crooked, corrupt and damaged little bums which they both CREATED! Their very bad parenting ultimately sent my older brother to state prison years later for ARMED ROBBERY !!! The story of how that all happened would take a whole book to tell in here.
That's his way to make up for the emptiness, loneliness and despair that very inadequate parenting has left him with, IMO. He's a VICTIM of faulty parenting like us kids were!
I've already said it but I'll repeat it - FIX YOU OWN FAULTY PARENTING - and then, you might be able to help your now DAMAGED child!
Good luck helping your damaged child,
Jim