William, my family is like that too. i divorced them. you seem to be stuck with them at the moment and personally, I think that putting a lock on your door is healthy. It means you know inside yourself that you are worthy of protecting yourself, that you trust your instincts. good for you! As far as developing trust outside of your family, no it isn't easy but you can. Growth is always built upon prior successes - in anything - so start small. It's never good to meet someone and automatically place absolute trust in that person. Take your time, listen to your spidey senses and only offer more of yourself as it feels safe to do so. You will make mistakes and get hurt, as we are human, so we make mistakes. Don't get mad at yourself! You will learn, just as you have learned how to be safe under the same roof with people you realize are not trustworthy. You are doing it! You posted here and that's a start. Now you can think about what i've said and judge for yourself if it fits for you. If it sounds like rubbish, let it go and ask yourself what didn't fit. Even that may give you a clue to what fits for you.
I hope this is helpful. If nothing else, know that there is someone who thinks you are moving in the right direction and i support how you are taking care of yourself!