Thanks so much for reading this, Alex, and for sharing a bit of your story! From the little I know about you, I find it hard to imagine you're prickly - and definitely not the kind of grumpy, selfish, nasty prickly I'm describing in this piece!
There is another kind though, and perhaps that's what this person meant with you - sometimes we can put up defences that keep people from getting too close, and it's not always something we're aware that we're doing.
Another option is that this person is projecting and thinks she sees something in you that is really an issue within herself.
And if she's right, and there's some sort of prickliness going on for you and you're willing to discover what it is, why it's there, and what you can do about it (because I know you'd be asking all of these questions if that were the case), what a brilliant idea to give you a little catcus with her loving suggestion to care for it!!
As for trying to impart these messages to those who need them...in my humble experience, that doesn't usually work. They're not remotely self-aware enough to even consider taking such information on board. They would see it as an unwarranted attack, be defensive, absolutely be unwilling and/or unable to see what they're doing. Usually, they need to have some sort of "rock bottom" moment in which they can no longer deny that their behaviour is adversely affecting their lives and relationships. It's that thing, y'know, leading horses to water... 😝