I recognise a lot of what you're describing. It is an all-too-familiar pattern.
You are the typical Mr Nice Guy husband/father who lacks self-esteem, masculine confidence and boundaries, and as a consequence sees sex as something he will only ever be "given" in exchange for doing all manner of other things.
This very poisoned thinking results in him doing more and more "chores" for decreasing amounts of (usually) crap sex.
That's because women do not respect and are therefore not sexually attracted to this kind of man (although they are usually content to let him rush around making their lives as easy as possible).
I'm a little short of time right now. What I suggest is you read these threads:
Get the books I recommended in the first thread (worth their weight in gold) and have a read and a think. Then post a bit more about yourself and your wife. We can take it from there.
The good news is that with honest self-examination, hard work and discipline on your part, you can make your marriage passionate and fulfilling again - or else if your wife refuses to take on her part of revitalising it, you'll be in a far better position to end it and find another woman.
Either way, it all starts with YOU.
S&A
"A man can be destroyed but not defeated" - from The Old Man and the Sea, by Ernest Hemingway.
Which I take to mean that every man has within him a spirit of relentlessness and optimism. Its already there; he just has to cultivate it.
