The older boyfriend your daughter is seeing would make any parent leery and uncomfortable. Remember, at 16, just about every teen will do the opposite of what her parent tells her to do. We understand why you have said she cannot see her boyfriend. It is the right thing to do. But she has to come to this conclusion herself. If you keep her from seeing him, she will most likely start lying about her whereabouts and sneak out to see him, causing more problems in the future.
See if you and your husband can come to terms with your daughter dating an older boy. Then explain to your daughter that because of the age difference and her boyfriend’s drug history, there will be some rules regarding the relationship.
While you commend him for trying to change, tell your daughter that until you are comfortable with him, she and her boyfriend can only be together when one of you is around. Have him over to the house, invite him out to dinner and/or include him in a family movie night. The more you know him, the more you will understand what she sees in him. It will also provide you with the opportunity to keep an eye on their interaction. This will be difficult on you and your husband, so make sure that the two of you are talking about it as much as you can.
As for your daughter’s sexual activity, this is definitely not what we as parents want for our children. Talk to your daughter about your feelings. You can’t erase the past, but you can keep the lines of communication open. Provide parental guidance and express the importance of what sex can do to a relationship. Make an appointment with a gynecologist so your daughter can talk to a professional and receive the proper education about the things she THINKS she already knows.
At this point, talk to your daughter about how the two of you will together tell your husband. This will be difficult for you, but the words and wisdom will come. Stay positive and calm with your daughter so she knows that when she confronts the next important step in her life, she can come to you without fearing your anger.