Thank-you very much for posting this thread.
It's examples like yours that illustrate why I recommend that young adults have 5 or more boyfriends or girlfriends before settling down to having children or marriage.
If you had had 4 or more boyfriends before this one, you may well have seen the warning signs as to how things would work out with him at an early stage. Or you may not have - because some people change with parenthood. And the vast majority of people change their behaviour for the worse after their honeymoon period is over (which usually lasts for 9 to 18 months after starting to live together).
Anyway. I can appreciate that this is a tricky situation.
Ideally it'd be great if you could reignite the passion between you. Or at least move it on to a more steady, loving, caring, long term thing.
From your description, there's the possibility that he's getting his sex from someone else. If not, he's masturbating.
Have you been nagging or criticising him over anything? If so, try your best to stop.
When was the last time you went out on a date? Even if it's something simple like a drink and a bite to eat?
The thing about the bj sounds like complete bs to me. You're too special, and yet he treats you like dirt? Pull the other one!
Sounds like he's making excuses because he's ejaculated recently.
If you are unable to reignite your relationship, it does put you in a bad situation - because of the children.
I've got a feeling that this may be beyond your control. That your partner is already looking to get out of this relationship and that he feels trapped and therefore resentful towards you.
All you can do is give it your best shot and see what happens...