I had night terrors as a young child and then had odd sleep walking/vomiting during a portion of my pre-puberty years. There was no diagnosis and I outgrew both. For the record, I had two loving parents, one a stay-at-home mom and a dad that worked regular 9-5 hrs. I had two older siblings that also cared for me.
My point is that you are just being hard on yourself by making yourself feeling guilty about your husband's periodic absence. The night terrors would most likely occur regardless. There is no explanation for them and they simply go away with time.
Now, if she is showing signs of stress like losing hair, banging her head, or something along those lines, then maybe she see a child psychologist. If not, all you can do is comfort her when they occur.
Something else you may want to consider is that when your husband is gone and you temporarily become a "single" mom, you will have more stress which in turn makes you more sensitive to your daughter's crankiness. So, inadvertently you believe her attitude change is due to your husband's absence and really you are more exhausted and less tolerant. Just a thought.