How can I deal with anger and depression associated with Caregiver burnout?

I have been dealing with my elderly mother's health issues constantly since her open heart surgery during May, 2009. I have lived and breathed hospitals/chronic care facilities/skilled nursing facilities for almost 3 years. I now have her in our home since October, 2011 and you would think I would now feel as though things are a little easier as I have in-home part-time care and still work. Quite the contrary. I no longer need to drive 33 miles one way to visit her at a chronic care facility. I spent all of the summer of 2009 on leave from my job sleeping at the hospital parking garage and 24-7 keeping close tabs on every step of her care. Frankly, it is because I have made this my life that she is still alive. I have documented every step of her care and have been instrumental in making sure that the right decisions were made. She has COPD, congestive heart failure and is otherwise of a very sound mind at age 85. Today I took off work for the day to accompany her to the GI doctor appointment for an evaluation. She is newly diagnosed with gallstones. She was on a ventilator for 2 years and is considered a "miracle" person to have gotten off of the ventilator, although she has a trach and it is opined she will always have a trach. I am beginning to get angry. For the most part I can deal with things as my job is my outlet and I work full-time. But when I come home from work at 5:30, I want to have some time for me and I am angry that after working 42 years I cannot take vacations and enjoy life. I have sought counseling and I have some close friends who care but I cannot keep venting on this to them as I will cause them to distance. I am not in a good place this morning because I chose to take off work for the day in order to go to this appointment this afternoon but this is yet another example where as a friend of mine explained last night....I chose to have her in my home so I now have the responsibility of a child. I never had children. I never had pets. I worked hard all of my life being a great daughter...taking my mother on trips galore and meeting her every need. I am 61 years old now and today I am just angry. Putting her in a nursing home is not an option. I have had enough personal experience to know that she would not last very long at such a facility as she has already gotten an array of hospital acquired infections and the pulmonologist has advised me to keep her out of the public until spring because of the flu. So this is my new life which is no life. Granted, I have it better than so many others but I am just too angry this morning. My morning will be spent on taking care of her needs. I have to get prescriptions refilled, contact a hospital for medical records, contact her doctor as I can't access their patient portal which I am doing all of the right things. I have one sibling who lives 4 hours away and he is useless. He came down recently prior to Christmas for the first time in 15 months! That was his duty visit. My mother and I have always been close. She is not abusive. She is sweet and is trying her best to have a quality of life. But at my age she was having her life and not taking care of an aging parent. I am sorry. This is hell on earth. I take time for me but this does not negate the fact that I am tied down granted my choice as my friend pointed out last night. Living 24/7 with an aging parent and feeling as though I deserve a life and getting increasingly angry is just what it is. There is no solution. I don't need advice on therapy (done that); making time for me (I do that); because at the end of the day,it is what it is. There is no easy answer. This is my new life. I told a friend recently well I need to leave work now and start my "other job" at home. Her care isn't even that demanding. I give her medications during the eveing and monitor her SATs to determine if she needs oxygen. But I am getting caregiver burnout here and yes I have researched this any nauseum and know all about the signs and suggestions. So I appreciate being able to vent today and I appreciate everyone on this group who can identify to some extent. You all get it. I am just angry today. I am sure it will pass. Tomorrow I return to work and will feel at least for a few hours like I have a life away from home.