Well, they obviously are annoyed that you quit for a competitor - they would not be that nasty if they did not think you were good enough to bring significant advantages to your new employer. If they really thought there had been interpersonal issues and your personality was to blame they would perhaps be rather happy you were with a competitor.

Such small mindedness is a sign that your former colleagues were not as deserving of your respect as you thought. That is a sad thought but let it go, and concentrate on your new job and new colleagues.

In the long run it is unwise to speak ill of people. You are no doubt making a good impression in your new firm and people will not find the bad-mouthing of you convincing and will have their suspicions of someone who runs you down.

They will get over it, no one is dead or injured, it will all blow over.