I am also a SAHM with school aged children who does art (and music) while the kids are at school (but don't have a cleaner, and only have a BTEC Advanced (or something like that, can't remember what it's called), not a degree in Art. So we're quite similar! Except DH seems happy.
I admire the fact that you got a degree in it, and that you've sold stuff, to me that is a measure of success.
I'm often confused about whether I should get a paid job when we don't actually need more money. I don't actually feel lazy because I'm doing music practice, having music lessons, doing art and housework before collecting the kids, then helping them with homework, talking to them about school and cooking tea while stopping every so often to break up fights. Nobody pays me to do any of it but I still feel tired from putting energy into it.
If your kids are at school you still look after them for 1h ish in the morning and 4h ish between school end and bedtime, so 5h ish in total. I find looking after children hard work! Do some people not think it is? I admire their coping abilities if they don't!
If I took someone else's children and looked after them for 5 hours, 5 days per week and weekends and they paid me to do it I don't think anyone would think I was lazy. But if I do this for my own kids (and don't have a paid job as well) I feel that lots of people on here will think I am. I find this hard to get my head round.
It seems that society only respects work that is paid and success is all about money. I feel some feeling of success if I pass the next grade in music, or perform well at a concert/gathering (usually for free), or finish a good piece of art. But on the few occasions I've been paid (and not much at all) I've felt a greater feeling of success, just the fact that I was paid, never mind how much. It confuses me that I feel this. Are things not to be respected unless someone has paid for them? Is it all about money? I know money is important and is a problem if you don't have enough.
I do think that if your DH is earning all the money then he shouldn't have to do any housework and only minimal childcare, and you should make his homelife nice for him when he comes home. I feel guilty that I don't keep the house perfect every day (sometimes it's very 'imperfect') because some days I feel I'm having 'mental issues' (slightly worried I've got something wrong with me, like my son who we're waiting for a diagnosis from paediatrician for).
My 'excuse' for not working and spending time doing what I want is that when I was working I didn't cope well with doing that and being a mother at the same time and was bad tempered with my kids. Doing a bit of what I want allows me to recharge and helps me be nicer to them when they are home. I must remind myself of this next time I feel like whinging to DH about how difficult the children have been! I was so (openly) irritated by their behaviour this pm and feel guilty that they must have felt I would rather they weren't there! (I'm having a 'mental' day). My son was being incredibly difficult, but the point of my non-working time is supposed to be to make me more tolerant and patient of my kids, so this pm I failed!
Sorry - this is just rambling with no solutions to the problem, as I'm confused about these things myself!