You normally need some "crime" to have occurred to sue someone, some violation of a law or standard. What exactly do you believe they have done to you directly? I think you'll find they haven't done anything, but people you know have
Yes the horrible truth is they generally don’t disfellowship people for talking to disfellowshipped family, especially if you’re fairly discreet about it. It’s much more subtle and nefarious than that.
For sure they’ve got more hardline about it recently, portraying good JWs in video and print as shunning family. But in most cases, the worse that would happen is removal of the dubious privilege of being an elder, servant or possibly pioneer. All depending on their local need for servants etc and the popularity of the JW who continues a relationship with DF family.
If push came to shove and they were at risk of loosing lots of lawsuits, I’m sure they could dig up plenty of dubs who continue to see their DF kids etc.