Accused of being a poor leader whilst at home looking after my baby

Whilst on maternity leave my male boss called me in for a meeting. During this meeting he presented me with a paper that accused me of being a poor leader, made accusations against my whole team for being ‘fortress administration team’, told me that when I returned there would be a new regime in which under-performance would need to be dealt with swiftly, went on in this vein for some time – and ended his paper by saying that given the list, my job description would need to be reviewed when I returned. When I pressed him for any examples or indeed any explanation whatsoever of where this astonishing attack had come from and why, he was unable to give me any at all. The last communication I had from my employer was my performance development review, which stated that I had exceeded expectations. Needless to say although I need to go back temporarily or pay back my maternity pay, I have another job lined up already. Should I have been put through this while attempting to be at home looking after my baby?? NO.