I would suggest keeping in mind that your child is the same person they were before they came out to you. That in the end, your child is still your child, and needs your love and acceptance.
As far as the sex talk, still have it. Remember that parents never particularly enjoy talking about sex to their children and that goes for the children as well. We have to have this conversation with our kids to make sure that if they are doing it, they are doing it safely. My family was big about "not wanting to hear about gay things" which is completely fine, because i didn't want to hear about their sex lives either.
Parents, your child came out to you most likely after years of trying to accept themselves and come to terms with who they really are. Keep this in mind when you find yourself feeling badly about it. Remind your child that accepting this will be a process for you too, because you are mourning the loss of the child you thought you had. While you still your child, parents oftentimes have their child's lives planned out, and that plan typically doesn't include harassment, bullying, and having a harder life based on the person they love.
Children need to understand this, so it is important to communicate with them. I recommend family counseling too! My mother and I went through it when i came out, and it was truly magical.
The last thing to remember if you suspect your child is LGBT, don't feel offended if you ask them and they lie to you, they have to come to terms with it for themselves before they can admit it to other people. The only thing you can do is make sure they know that you are there and love them no matter what.