Clematis: Can you experts ID my new clematis?, 1 by Cannd827

Cannd827 wrote:
My new clematis looks like the one above. The backs of the flowers have lighter purple and white steps almost. Im trying to id which grp is a part of to know how to prune it in winter etc.

I was told to cut it to about 12 in this year after frost. Was it too soon as there seemed to be blooms on our still unopened but much liked wilted after first frost.

How would i care for this next winter and do i need to cover the pot and remaining vine during the winter? Would a plastic garbage bag help? Does it have to be mulch or something?