Learning Spanish on my own (and teaching it to the kids)

I have always wanted to learn Spanish and have always been ridiculously jealous of anyone who can speak more then one language.  My grandma spent many years in Spain and my mom was born there.  Both my mom and grandma used to know a lot of Spanish but they never spoke it to me.  I was never able to take Spanish in school due to a scheduling conflict with band.  I did take two classes of Spanish in collage and really learned very little.  I remember watching some movies in Spanish in class and we were all shocked at how little we understood.  After going through 4 hours of class for 3 days a week for two months straight we thought we would understand at least 10% of what was said but it was closer to 1%.  Now I have a little time on my hands an a strong motivation to finally just do it.  I want to teach my kids.  That is the mantra that is going through my head every time I think I am just crazy for even trying to learn Spanish.  No one else can do it, it has to be me.  If I can teach myself how to run a small business office, and make cheese then certainly I can do this.