Have I been poisoned by the copper pot I just bought?

Yesterday I bought a used pot in a Goodwill thrift shop for $10 that I thought was a copper coated on the outside stainless steel pot, but after reading about copper pots on this board I now think it is a stainless steel or tin lined copper pot, as it is very heavy for its size. There is no brand name on it. The pot seems to have been made by spinning as the interior has small grooves in it, and looks high quality by its intricate design and construction.
My worry is I cooked a mixture of broccoli, carrots, and snap peas in it and ate about half of it and left the rest sitting in the pot for several hours. When I looked at it later the interior of the pot had turned a blue violet color where it was in contact with the vegetables. What could this be, and is it poisonous and should I throw this pot out?
The exterior of the pot also is covered with what I think is lacquer. I scrubbed the pot with barkeepers friend and a steel wool pad and got the violet colored tarnish off the inside and most of the lacquer off. I also tried to burn the lacquer off by putting the empty pot on the stove with the gas turned up high but quickly shut it off when the outside copper part of the pot started to turn blue violet colored too.
Is what happened normal and does one have to season copper pots, or maybe is the coating on the inside too thin, although I can't see any copper showing on the inside?