I feel like a bad person

After months of trying we figured out my husband can't have kids, so we are using a sperm donor. While the whole process is very stressful and we are still upset about him not having kids. But we are moving on with the process because we want kids.

The reason i feel like a bad person is because I'm so scared that our future children will be born with a birth defect or some kind of genetic disease and I won't be able to handle it. I know that I will love the child regardless but the stress and extra commitment to their medical needs is something I think I would fail at as a parent. Am I the only one who thinks about this kind of thing? Like down syndrome or a muscle disorder. I see how some parents deal with their kids special needs and they are so good at it.

My husband has always had a feeling he was sterile. And I have always felt I would have a child with a disorder, maybe as some sort of punishment to the child for something I have done(not to say children with disabilities are a punishment, I know every child is a blessing)

I don't consider myself a bad person but this thought it's just eating at my so much lately. How do I deal with this? Sorry for the long post and I didn't mean to offend anyone