As always, I am sorry you--or anyone else for that matter--is going through this. It's just as wrong as wrong can be.
That being said, I actually believe this is a fairly common and in fact completely understandable reaction, as many of the above comments have confirmed.
When a previously faithful person leaves a group it raises all kinds of issues: some explicit, others less so; some clearly understood by everyone; others more subtle, but nevertheless there.
As others have commented, your family members need to reaffirm to themselves that they have "the Truth." This is cognitive dissonance and confirmation bias in action. Behold and learn!
They also possibly hope that somehow (by some bizarre theological calculus) their zeal will lead you to return. Remember, they're told Job prayed on behalf of his errant family members. They might be trying to work a deal with God your your behalf! If that's the case, at least their motives are pure even if their actions are maddeningly illogical and frustrating.
But I have come to see that there is in fact a more powerful, and indeed a more insidious reason, for this reaction on the part of those still in: They need to distance themselves from you in the eyes of the group.
You well know how important appearances are in the cult of JWs. Whenever someone leaves a group, any group, those that remain need to take some positive, visible steps to prove to the group that their allegience is still to the group and NOT to the "disloyal one" that left. In the cult of JWs, increased activity is the visible proof that is expected. This is what they are doing.
I believe that this behavior is happening at a level that is just at, or more probably just below, the conscious level of the individual.
Are you familiar with the Asch Conformity Experiments? If not, you should familiarize yourself with them. It's an education!
Again, you have my deepest sympathies. As you know, I utterly detest this cult for what it has done to my family and thousands of others. Our only reasoned response is to educate ourselves so that we may heal ourselves and then in turn be in a position to help as many as possible leave and live fulfilling lives free from the mind-control of the WTBTS cult.