Remember you are detaching with love. You aren't being spiteful or mean. I agree with you about not doing the gardening. I also agree she should ask you nicely, but remember you weren't a good husband and you coming off as a a$$ won't help.
It's a delicate balance of actions and words from now on. You arent your W errand boy, so let her know that in a lovingly way. "I understand you want me to work on the garden, but I'm not comfortable being your errand boy, I'm your husband". Leave it at that.
When it comes coparenting the children, you get more bees with honey. In other words, be a man, but don't be mean. Keep your tones neutral. "Hey, W I'm coming to get S13 at this time". Leave out the so have him ready part, that will make her defensive because your were demanding. And demanding is not what you are trying to achieve respect is what you are after.
Start respecting yourself and loving yourself and the rest will start to fall in place. A person that love and respect themselves don't allow another to disrespect them.
M:37 W:37 T:11 M:10 S17, S13, S10, S4 BD:06/28/17 OM confirmed 07/20/17 Recon the M 10/29/17 Working hard:2gether
Onward and forward
This process is not a sprint it's a marathon! Patience, Patience, Patience.