I have not brought this up before, but this is an interesting thought which might or might not help you.
Many years ago, I lived in the city of Gent, Belgium. There was this 'social living' complex in the city. This is a huge apartment complex for families with low incomes. At least 8 JW families lived in that same complex. (heh, makes one wonder why). I hung out there a lot as all the JW families were my friends. Then, one day one of the families their son got DF'ed. The mother was devastated. I was told that JW's no longer talk to people who are DF'ed. But a few days later, I saw the JW mother with her DF'ed son sitting on the front lawn. I asked one of the other JW's.. how come they are hanging out together, I thought they were not supposed to talk? I remember the answer to my question quite clearly.
They told me that it was different for 'family'. The bible points out the importance of family, and the honor which one should have for one another within a family. So they said that, if someone gets DF'ed, the immediate family can still make a personal choice to talk to them or not. If they do, they are no longer allowed to talk about spiritual matters at all, but they are allowed to talk about anything else.
This is just a thought, but I know that my memory is right. Is it possible that those JW's were member of a more liberal KH, or have the DF rules changed.. I have no idea.
Then, one of my best friends here in NY her son was DF'ed for sleeping with a girl whom he later married. She still visits him, especially since they have a baby now. She doesn't actually 'talk' to him, but she does visit the baby. She was also reprimanded for attending his wedding.
What I'm saying is, there might be hope. You might end up not being completely cut off from your in laws, but then perhaps I'm just naive. One way or the other, good luck to you.