Re: When your family resents Aikido
Reassure your husband and child (individually) that you still love them and that you are not planning on getting a divorce. "Obviously," from your husband and child's view, if mom has been at home for over ten years and then suddenly gets a job, starts doing Aikido, then she must be leaving -- maybe she already has a boyfriend? In the absence of hard data people tend to invent worse case scenarios to explain/rationalize your behavior. Your family likes having you around and so acts up to see if you'll pay attention to the squeaky wheel the way mom always has.
Of course, if you and your husband have been drifting apart then you'll be taking stock on if you want that drift to continue into a divorce or if you share enough values, beliefs, etc. that the marriage itself could use a tune-up. If you still like the guy then see what sort of "tune-up" things would work for both of you while also allowing you to continue with your Aikido practice.
When I started Aikido my daughter, around eight at the time, was bothered I was gone in the evenings. I switched to mid-day classes (when she's in school) except for one evening class per week and even there I make sure that the family understands the Aikido is a second priority.
Seminars would be tough as you'd be gone pretty much all day or weekend. In my case I've pretty much always limited myself to a couple per year.