I've changed and everyone likes me now - everyone except me.?

I have never been an assertive "go-getter" type of person. I genuinely don't sweat the small stuff and am usually happy just to go with the flow. Some may call me a "pleaser". EVERYONE in my life has told me for years that I need to stand up for myself and be more assertive, calling people out if they disrespect or insult me. I have been started to push my comfort zone recently and EVERYONE - friends, family, my wife, literally all the people in my life - have said they like that I'm not being a "doormat" any more. My wife actually said the sentence "I am REALLY liking this side of you!"

Sounds great, right?

Well, no, because I HATE being like this. It's mentally and physically draining, and the last 2 nights I have waited till my wife has fallen asleep and cried from the stress. I don't dare show that to anyone though as those same people have ALL told me some variation of "don't get cross", or "you can either moan about it or do something about it" etc - basically I get no sympathy at all, just cold, emotionless advice.

So my question is: how can I manage this better? I am finally getting respect from people and they all seem to like me better, but I do not like me better. It feels so inauthentic and I feel like by being this way I am admitting that who I actually am is unacceptable.