Age Appropriate Honesty

So here's the problem that I'm anticipating -- already. My kids are only 4 and 2 right now (and the 2 year old barely talks) but I'm already stressed about how to deal with questions from them about where we go (meetings, therapy) and why. I know we're not going to lie to them. When my husband went to 30 day inpatient, we told them that he was going to a sort of 'daddy camp' so that he could learn to be a better daddy to them and a better husband to me. I didn't want to tell them anything like 'he has to go away for work' because I knew there'd come a time when they'd resent the lie. So if we're not going to lie to them about what is going on, then how do we stay age appropriately honest?

How does a person raise healthy, high functioning kids when they're living with an addict (in early recovery, but an addict none the less.) How do I promote healthy sexual development in my son, for instance, knowing that he's going to have a genetic predisposition to addiction? I worry all the time about the examples we are setting (my Husband of addict and me of codependent) knowing that our kids learn more from our actions than from our words.

I feel confident in our treatment providers right now that they (my therapist and my husband's therapist) have both of us on good roads to getting stronger and healthier, but I still worry about the effect this has already had on my kids, and the effect it will continue to have as we continue to try to get ourselves healthier. I suppose I'm already ahead of the game because I'm actually thinking about these things, and worrying about it, but am I going too far? Am I 'future tripping'? I'm realizing more and more that we need to be cognisant of our issues and motivation all day every day. It's exhausting!