I understand your frustration - going thru some of that myself!! But it really CAN be done - check out the resources on SparkPeople for ideas - there are exercises you can do at work, in the car, while waiting in line - you could go to the gym before you get ready for work and that might help you get to sleep earlier - or simply do exercises at home with DVDs and a few inexpensive aids such as a jump rope, resistance bands, etc.
Once you get back into the swing of things, it will get better - you don't have to do 'all of it at once' so look at successes in a different way - in other words, not gaining any weight is more of a success than gaining - gaining 5-10 lbs is better than 20-25 - exercising for 10 minutes is better than not exercising.
Use the trackers and check out some of the SparkTeams that might help you - Some of the teams I like and think you might like include the Official 10-minute Daily Exercise Streak Challenge, Starting Over Weekly Mini-Challenge Team, 10k Steps A Day and Motivation & Positive Attitude Plan - but there are so many to choose from, you can have a great time looking for the ones that seem to fit you best! In fact, I suggest joining more than one group, post your intro there and write blogs as often as you can - you will find tons of friends and support that way, I promise!!