Good to hear things have calmed down. I am sure your decision to speak to a counsellor is a good one, make sure you choose carefully, as well. It absolutely is the right thing to do to have a space to talk things through without it turning into an argument, and a good skilled counsellor will help you both do that.
Hold on to this post and what you've said here and don't minimise what he did. I absolutely understand people can behave badly in times of stress but he did push you over - that's never an acceptable way to behave in an argument. If I'd learnt that sooner, and not been so quick to understand and explain away reactions in times of stress, I would have found things easier, and so would my kids.
@ilovemyspace, you're right, noone is perfect, and relationships always need understanding and compromise, but the OP does literally say "he pushed me over". That's not necessarily abuse, true, but it's not acceptable behaviour. I've come back to this post not to start an argument with you but because it really resonated with me. No, pushing and shoving really isn't how life and relationships should work, though I used to think it was, too.
Sorry for the essay, OP, but I'm sending you all best wishes and strength as you deal with your parent's diagnosis and these difficult times. However deeply you understand and sympathise with someone, to be left frightened and shocked by their behaviour isn't OK. Stay strong, stay calm, and stick to your instinct of bringing this out into the open and talking about it with a counsellor.