Dear Saddest,
You are not alone.
I too have been married for 7 years, and DS (DH's stepson) and I have not seen my ILs (MIL, FIL, and SIL who lives with them) since our wedding. I have only ever met them 3 times, one of which was my wedding day!
They have never EVER visited us, even when we only lived an hour's drive away from them.
Dh visits them every 2 months, but whenever he suggests DS and I visit, they are always "too ill". When he booked us into a nearby hotel for a weekend visit a couple of years ago, SIL threw a huge tantrum because she was due to have some hospital tests the following week and was "too stressed" to cope with visitors, so we had to cancel.
18 months ago, I accidentally came across an email SIL had sent to a friend claiming that amongst other sins such as "getting married in a registry office" :
I had refused to visit DH in hospital when he had a life-threatening accident, that I was a hopeless alcoholic who has ruined him financially by drinking away every penny he's earned since we got married, and that he had actually left me for a while, only returning out of concern for the welfare of my poor little DS.
There is not a word of truth in any of this.
Dear Readers, when we married he was £30k in debt, had never stayed in one job for longer than 2 years and was living in a grotty North London shared flat with a friend from Uni. He is now debt free, has been running a thriving business (which we set up together) from home for the last 5 years and we live in a lovely house in a beautiful part of the country. We are very happy, and have been since we got married.
I can only assume that because I am 5 years older than DH, have an illegitimate child, a job they can't understand and have been unable to provide them with grandchildren I am damned beyond redemption in their eyes.