Lilac Questions

[Kevin Buckley]

I received a lilac bush, about 3 feet tall, three months ago.

I didn't have a place to plant it, so I left it in its pot.  Well, three
months later, the bush is not happy.  The leaves are wilting and have a
white deathly look to them.

My Question:

I live in Wisconsin.  Should I plant this lilac in the ground, so close
to winter? Should I move it to a bigger pot?  Take it inside for the
winter?

Thanks for your help!