Ive just done something assertive and now im shaking.

[GeorgiandI]

Im literally shaking and my heart is beating. I am NEVER assertive and I may have come across a bit aggressive which I think was because I was so nervous which I regret.

Now im so worried about the ramifications of this, of hurting the other person's feelings, they'll tell everyone else and everyone will go against me.

Listen to some cardi B and your feel brave and sassy in seconds.
Unless your a general mean person, no one pulls people up on their wrong doings for no reason, remember why you did and move on!
Good luck

Well the next day I got an earful from the person saying that they were surprised that I said what I did and it was really rude of me and that I should show them more respect. I didn't apologise for myself and tried to fight my ground but have come away deflated and just feel rubbish.

Oh OP stand by your convictions. Their response is irrelevant really. You did the right thing. You've clearly touched a nerve. So? Well done for not apologizing.

Well no ones going to like you standing up for yourself, especially if they’re used to you being a push over!

People do tend to have a strong push back at you when the gentle push-over finally snaps... they want you to get back into your usual dynamic.

They’re not going to validate you or congratulate you on standing up to them :-)

So don’t be dismayed, you are still being great. Don’t let them put you back in your box. You just climbed out of there!

Well done. Do not apologise!! I bet it took an awful lot to push you this far.

I stood up to someone more senior at work a few months ago who had spent years bullying people and talking down to everyone. She just caught me on a bad day and I told her I wasn't prepared to be spoken to like that anymore.

She was shocked and then ok at the time, then later told all and sundry how mean I'd been, blocked me on social media and intermittently ignores me. Thing is, it's far better now! Everyone knew what she was like and took it with a pinch of salt. I don't miss the fake forced contact we had.

She also knows if I see her doing it to anyone else I'll challenge her and since getting a promotion I also now have the authority to deal with her. It's better for everyone and I'm bloody glad I did it.

Well the next day I got an earful from the person saying that they were surprised that I said what I did and it was really rude of me and that I should show them more respect. I didn't apologise for myself and tried to fight my ground but have come away deflated and just feel rubbish.

OP respect needs to be earned.

What did you actually do? We can think of a kick ass response to that if we know the general gist of it.

Glad you stood your ground. If they can't accept a boundary you've put in place for yourself, that's their issue, not yours.

The more you are assertive, the easier it will be. You'll find the line between assertive and aggressive. Also, aggressive is sometimes justified.

As long as you are completely certain that you are in the right, and that what you said was reasonable, then.....fuck'em!