toy poodle not accepting new puppy

Question
We have a 5 year old toy poodle.  During the past year her seperation anxiety has become worse, so we decided to get a new puppy so she would have a friend when we are not home.  We have had the new toy poodle puppy for a week today.  She is 7 weeks old.  Our 5 year old is not accepting her at all.  She has never been aggressive before this, but she growls, barks, nips at and has even attacked the new puppy.  Both of my sisters have toy poodles and she has always played with them and not had a problem.  Is there anything we can do to make her like the new puppy?  Did we make a huge mistake?  Can we expect it to get better or worse?

Answer
Good intentions, but sadly I say that my experience has been adding a dog will not resolve or curtail separation anxiety.

It has only been a week, and it may not be a right fit in the long run, but try backing off a whole bunch! Maybe it's just too fast for your older dog to have time to accept the new dog.Try separating them  with puppy gates so the puppy will be safe and pair things that your older dog LOVES only in the presence of the new dog.

Avoid having special alone time with your older dog, only good things in the presence of the pup!

If possible have someone knowledgeable in behavior problems assess and come up with a program of modification.

In general, it's usually owner and dog who have to make some changes to help curtail this very complex problem.

If after a few weeks you see escalation or no improvement then maybe that would be the time to consider rehoming.