Train, I'll throw in too. Maybe give you some perspective from your H's point of view. Sorry it's *me* related, but I hope it gives you something to chew on.
My WAW had just quit working and was going back to school when she became pregnant with D13, our first. It was a very difficult, life-threatening pregnancy, and she was unable to continue school.
We both valued the SAHM. We both thought it best that the kids have someone at home, rather than being put in day-care. (no offense to those who choose daycare, we felt strongly otherwise) We both thought it best that mommy would be waiting for them when the school bus brought them home.
We knew it would be a challenge living on one income, but we thought it was worth it. I can't emphasize enough that we were both in full agreement on the choices. We both knew that W would go back to work eventually, but we never set those specific conditions up.
W was a very good mother. She is highly organized, and got involved in all kinds of extra-curricular things for the kids. But I don't think it was enough for her.
W just went back to work this winter, as part of her WAW exit plan.
Looking back now, I see nothing but red flags.
W had always been insecure. She was always afraid I would leave her. I never gave her any reason for this and never understood it. I now believe it was because I was successful, well educated, mobile, and she was less educated -- she was afraid I would eventually tire of her. When she became a SAHM, I think this worsened. She felt even less secure, no independent income, out of touch with the job market. [ringing a bell with you?] She was totally dependent on me.
Personally, I didn't think I would mind the SAHM. But now, I realize, that sub-consciously, there was stuff going on. My W was totally dependent on me. I guess I was always a bit of a father figure to her - nothing weird, but W's father passed when she was 18, and I am 9+ years older than W. W's total dependence on me as a SAHM probably made that worse. She commented to a friend recently that her big fear in even trying to R with me is that we'll never break the parent/child financial relationship we have and be equals in the M.
Now I also realize that by staying at home, she saw less of the world, and her universe shrank. We had less to talk about when I came home from work. She progressively understood less and less about what I did for a living, and was more intimidated by people who worked with me. Again, sub-consciously, she became less interesting to me, and I started pouring more time into hobbies and less into her.
So, knowing of her insecurities and need for independence and need to engage with people (she's very social) I celebrated her going back to work this winter. Of course, she was "done" by then, in an A, and took all my encouragement and happiness for her as insincere. Now she has all kinds of work related stories and angst that we could share - but she's not into talking to me about it.
And now, when she comes home at night, dressed for work, having put in a hard day, it's just damned sexy. I find it very attractive, (like clear the table!) and I realize now just how much I value and respect her independence.
So looking back now, if W had gone back to work 18 months earlier, I think we would not be where we are today, and I think half of our problems have already been solved by her returning to work.
But I digress...
So, my advice, from my perspective, is that yes, you should resume a career, at least part time. You have an inkling of insecurity and doubt about H leaving again. That's something you have to deal with separately, but if you at least have your toe into an independent outside career, you won't be sub-consciously feeding that fear, you'll be starving that fear.
And H says he will support your decision either way - that's great. Know that men have this innate "I'm the provider" need. Some might be intimidated by an independent W, some find it attractive. Being part time might let you get the best of this without pushing it too far either way with H.