A do-it-all mom,feeling so overwhelmed and burnt-out,and I feel guilty for it.?

I am married and has 3 young kids.For 9yrs now I have stayed at home to raise my kids,make sure that their needs are met.I drive them to school.do the laundry,chores,errands,tutor them,etc.I do this also to help my husband financially,since it will entail more expenses if I work and then we have to shoulder schoolbus service for the kids,a tutor,and a maid.I love my kids so much,but lately I feel like I am so exhausted physically doing all the work myself.I tend to yell a lot and I don't get to enjoy my kids anymore. Even tutoring time is a chore for me..I hate teaching,and I feel so drained out esp when preparing for examination week. Like today,I felt like I spent the whole day yelling and getting angry with my kids. Now that they are asleep,I am weeping because I failed to show my love for them today. My 9-y.old kid got so scared of me,bec she tried to wake me up after I dozed off (which I have been wanting to do since afternoon since I don't even get time to nap)..I got angry with her for waking me up. I just felt too tired..and I felt it is so unfair that I cannot even get enough rest. The kids won't let me.They're constantly asking me to do things for them,..you know how young kids are. I guess I just want to talk to mothers like me who love their kids but sometimes fail at being loving and lovable. Pls.advice.thanks.