OK, a couple of things to consider:
First of all, seeing him on the sly automatically make this whole thing suspicious. That, and the fact that he's legally an adult and you're legally a child puts another spin on it. (I'm not suggesting you're immature, I simply mean 'child' in the strict legal sense.) Now combine that with his history of substance abuse.
What parent
wouldn't be concerned?
Your dad, by the way, is absolutely right about substance abusers. They are users of people, of drugs, they are master manipulators.
Before you get all red in the face and start frothing at the mouth, I'm not saying that your current bf is all those things. If he had a habit, and he kicked it and has maintained the fortitude to steer clear of drugs, then that says a great deal about his strength of character.
So to the issue at hand: Your parents are the
only ones on the planet that can be guaranteed to have your best interests at heart. Granted, they may not have the full story and they may be irrationally judgemental, but the point is that their concerns are based on legitimate worries.
It will be up to you to prove to them that your new beau is a wise choice as a potential mate. You'll have to be calm, rational, factual and clear-headed about this. So talk to them, adult to adults.
DON'T:
- Get into the "I'm a big girl and I can make my own choices" fluffery. That will only damage your case;
- Get your sister involved. What happens with her is entirely irrelevant;
- Get all upset and crying and teary and all the rest. Your logic will fly out the window when that happens.
DO:
- Keep it factual;
- Understand that you know where they are coming from and that their concerns, in their mind, are legitimate; and,
- Express your appreciation for their worries, because they truly do want to protect you from danger.
Good luck!