Hi I would be happy to assist you in understanding your dream. I feel this lion is representing your ex lover. Perhaps your ex lover had a bad temper? or over bearing, or dominate, prideful? Animals will often times be a representation of characteristics for an individual. Since you were not trying give affection to this lion could be representing how you perhaps tried to deal with your relationship relating to your ex. Was he easily tempered? A sofa usually is symbolic of "support". Such as emotional or physical support in your life or relating to others. Your hand represents your works in life. Since the lion had its mouth on your hand to devour, perhaps your ex caused a lot of damage in your life and may have affected your ability to live life. Does this song mean anything to you personally? Sounds a though you were set free from the grasp of your relationship with your ex. If you have anymore questions feel free to ask.
Sounds to me you have a very clear understanding of your own dream. :-) Back doors usually represent things coming back in to your life or things that are in the back of your mind thoughts feelings etc. The ex lover could just be symbolic of your relationship with him and what he represents to you. it maybe similar in some way to the situation you are in now.