....Well I'm not sure how much you can handle on your plate right now, but I don't see why you can't have both. Get a job and get an education on the side. The only thing is, your education is going to take much longer with a full time job, but its not impossible to take one or two classes with a job and kids.
In the end its up to you. Honestly, you aren't living for yourself anymore with 3 kids. You're going to have to do what is best for them.