D..
Were they angry that you "trapped" their favorite by getting pregnant? Is that what this is about? They were ugly to you, trying to make it that it's your fault that you got pregnant?
Are you getting child support from him? Does he see the baby? It sounds like from what you say here that you two don't live together.
When you say that the father doesn't care or understand that you aren't comfortable around them because of their disrespect, do you mean that he doesn't care if his family sees the baby? I'm not sure from what you say...
Have you told them how you feel about them? That they have soured your relationship because of their attitude towards you? Honestly, I think you should tell them. It's NOT just your job to forgive and forget. It's their job to own up to their own behavior, and to treat you respectfully now.
Try to work this out. When they have "slick comments", tell them "What you just said really bothers me. I feel that it's disrespectful. I need to get off the phone now." That will teach them that if they want to see their grandchild, that they can't get away with talking ugly to you.