Thanks for sharing your concern here on PsychCentral. My personal opinion is that one overcomes a lack of self-confidence via accomplishment. One perhaps starts small with things one pretty-much knows one can do. And then one builds on those. Success breeds success, as the saying goes. The other option, I suppose, is to simply jump into the middle of things, make stuff happen, & be okay with failure if that is the result. See it as a learning opportunity. That's not a method I'm particularly comfortable with. But I know it is one that is often recommended.
The other piece to this puzzle though, I surmise, is one of not wanting to appear less than capable in front of your spouse & attempting to protect yourself by becoming defensive, which then leads to argument.
This, of course, is a dynamic I suspect every couple has to deal with to one degree or another. I know I've certainly been guilty of it over the years. There are, I would guess, probably whole books that have been written on this subject. So I doubt it's something I would be able to make much of an inroad into here.
My one suggestion would simply be, if-&-when you can, to try to pause before you react. If you can allow just a few seconds to elapse before you respond (such as to your husband's observation regarding the hose) it may give you the opportunity to formulate a more considered response, as opposed to just "shooting from the hip", as we used to say, with the first (probably defensive) thing that comes to mind.
Here's a selection of articles, from PsychCentral's archives, that I thought might provide some useful information regarding your concerns, the first by our host, Dr. John Grohol, Psy.D.:
https://psychcentral.com/blog/6-tips...dium=popular17
https://psychcentral.com/blog/positi...dium=popular17
https://psychcentral.com/lib/self-es...that-can-help/
https://psychcentral.com/lib/12-simp...dium=popular17
https://blogs.psychcentral.com/imper...dium=popular17
https://blogs.psychcentral.com/nlp/2...nto-arguments/
https://psychcentral.com/blog/the-7-...relationships/
https://psychcentral.com/lib/10-rule...couples/?all=1
I wish you well...
