Hi Dianne! I agree that what's normal varies, but here's how it works with my fam-i go home to visit every 2 weeks, sometimes more, but the more usually consists of just seeing my sister since we're closer. I talk on the phone to my parents probably twice a month or so, but my sister maybe onece a week. it's a lot different for my sister though who is married with a young child. i think she talks to both of them (my parents are divorced) and sees them a couple times a week. But also she lives in the same town as them, whereas i don't (i'm about an hour drive away).
My advice is to set some limits for your contact with them and try to explain the best you can why you are doing it. They may not be happy about it, but i think their discontent is better than the possibility of over time getting to the point where you're bitter and then there's even more of an estrangement.