This problem arises from allowing dogs to sleep with you and basically be with you all the time from being puppies. You might think it's better for them at the time but then they get to the point where they are unable to cope if left only for a moment and that has to happen sometime. They have developed an over-attached relationship with you and the implications of this can be even more distressing than a dog that spends too much time alone but is more used to it.

Dogs should always sleep downstairs in their own beds from being pups. Having that time to themselves teaches them to not mind spending some time alone plus it cuts down on the possibility of the dog developing dominance troubles by being allowed in such a key area as the master bedroom where they think only the alphas should be.
As she is now getting on, this dependancy is getting even higher and her age makes her less able to cope with these stressful situations.

A tip is to have greetings warm and welcoming and departures kept cool. In your case, you might be having the departures warm where you try to reassure the dog or whatever and maybe have greetings cool and angry where you are annoyed at the dog barking or maybe being destructive in your absence.

Go through some exercises that teach your dog to learn how to spend some time alone. Leave your dog in one room and leave the room, closing the door behind you and stand on the other side for a few seconds or even less. Go back in and praise her before she has a chance to start panicking, maybe giving her a small treat or a big fuss. She'll start to realise that, even though you leave, you always return so she doesn't need to worry. Keep doing this just for a few seconds then start to increase it a little.
After a while, you might just leave her indoors and go outside, maybe walk to the garden gate and then back to the house. Then graduate to having a quick run around the block in the car and, when you return, give her plenty of praise.
Remember not to make a fuss as you leave the room. Ignore her as you walk out.

Also, if she sleeps with you, start to concentrate on having her sleep elsewhere as she gets better. In a dog bed on the landing at first and then move her downstairs later on.

People make the mistake of thinking that loneliness causes this but it is not. Getting another dog for example will not help the behaviour at all. It is people the dogs craves simply because it is not used to being without one in it's presence.