I can say with a high level of accuracy that your sister is a completely self absorbed and narcissistic individual, and she sounds like she may also be sociopathic. I see zero ability to empathize with anything you or your husband said. Your husband was very cordial and honest, the fact that this woman came back with that amount of venom shows that she indeed did feel guilty, and yet again instead of choosing to see from anyone else's perspective and actually showing compassion, she went on making excuses for herself.

My girlfriend has the same type of family. They don't care about anyone but themselves, they only ever call when they need something, or they need a ride, or when they have problems. They make her feel guilty for not coming around them, but when she points out why, they come back with nastiness and insults.

My advice? Don't go around them anymore. At all. Only allow people in your life who actually care about you and your family. Siblings bond when they are younger, but many don't maintain close relationships once they become adults. Your sister sounds like a real mess. Your life will be better off. Good luck.