Been there, done that! Although, I was also pursuing a degree at the time. I don't know how I did it. The best advice I can give is to treat time as your most precious resource, and always triage. Give up things like television, video games, nights out with friends, sports, etc. The wife and kids must have high priority if you want to keep them. I always felt that I was not performing well at my job, but my management was always happy so I guess I was "good enough". I only managed a 3.75 GPA, but I guess that was "good enough". I did not take on any new work on my side project, but I somehow managed to keep it going (and it is still going today).