Backbitting people and seeking forgivness without apologising to them and not feeling regret

Asalamu alaykum wa rahmatullah wa barakatuh I remembered that I have backbitten my parents and sisters and I really know how wrong and how unfair it is, I want to repent but I can't tell them about it and apologies because I'm sure it will cause big problems and break their hearts and I don't want that, but the most important part of repentance is regret, and I use to feel regret from the depths of my heart but now I stopped feeling regret and the problem is that I repeated that sin, so do I have to re-new my repentance? And does backbiting your family and not feeling regret make the situation worse which may lead to that Allah will not forgive me unless I apologise to them? But I always make the best dua for them and I make them happy and I hell them and support them so would this + not getting back to this sin + regretting it alone be good enough without apologising? I really can't teLloyd them I was backbiting them please help And is saying mean things in your head about someone considered backbiting? And would you please tell me how to feel regret? I'm so sorry for the trouble May Allah bless all those who help me and make them as hapPygocentrus as they are going to make me feel and even more happy in this dunya and in the afterlife Jasakumu Allah alf Khair