Love life=mine!

So, I'm a 20 year old woman and I'm in a relationship with this wonderful guy. The problem is that my sister and her husband don't trust him because he's on probation for street racing. I really want them to back out of it, but I don't know how to tell them that without being bitchy. Any advice?

be mean. I know this isn't what you wanted to hear but people will only respond to very direct commands. Say "Look you've told me your concerns and you've stated your case. Now it's time for me to make a decision and you need to respect my decision even if you believe it's the wrong choice. It's my decision to make." If they refuse at this point then you stop talking to them until they contact you and tell you they understand. Sometimes the only way to make someone respect you is to cut them out of your life. as painful as that can be it's not your fault if that's what has to happen.