Hi Kate
You are obviously in a difficult situation. I'm anything but a relationship expert, so I'll leave that to someone else. However, here are two things that you already know: as much as this hurts,
the pain is temporary; and
your children need their mother, so continue to stay strong, at the very least for their sake (in addition to your own). You already know these things -- just don't allow your emotions to cloud your good judgement. Easier said than done? Yes, absolutely. You can think of this as one hell of a PD challenge
Finances are obviously an issue here, as you stated. I see a couple of possibilities. First, if you come to some sort of temporary arrangment with your husband and get your job back (or similar job), you can work like hell to pay off that 10k and get out of dodge. It may require some lifestyle changes, but it's reasonably achievable within a short period of time. Is it as short as you want it to be (immediate)? No, but it is a way out, albeit an uncomfortable one.
Second, you said you have family back in Toronto. Lean on them. Perhaps they're willing to help with plane tickets and short-term accommodations for you and the kids. If they are unable/unwilling to assist, use any available credit on your credit card to buy the tickets. You could even apply for a new card, buy the tickets, and then declare bankruptcy to get you out of the whole mess. Yeah, that is a crappy option that I'd avoid like the plague, but desperate times call for desperate measures.
You are strong -- you posted this out there for the world to see. You're ready for a change and are taking the proactive steps necessary to make it happen. You know you can achieve a greater life for yourself and your children, and
that is something worth holding on to and fighting for. You might not be able to see it now, but you have already taken the first step towards achieving the great life you want. Too many people embrace the mouse within, and life their lives of "quiet desperation" (Thoreau). That is obviously not for you, nor should it be. Remember that this, too, shall pass.
- Tom