How can you be helpful to others without losing yourself completely in the process; or viceversa...?

Be mindful of your breathing: inhalation-----exhalation it is a cycle and it is balanced and both parts of breathing create a complete cycle. You already know that what you are doing is not working because it is not balanced. First, take care of your own needs so you will not build resentment into helping others, and get good nutrition and rest or you'll just be compounding misery. You can not possibly be extending help and health to others if you can not extend it to yourself. Look around you and observe friends who have balance and find out what they do and don't do to live in harmony .