Give the gift of your absence to those who do not appreciate your presence....
Above all, do what you need to do for yourself. If you are giving the gift of your absence, make sure it is for the right reasons. Not out of anger or revenge, but because it is the right thing to do in the circumstances.
If someone has been oblivious to you and your feelings, abusive or disrespectful, then walking away is highly recommended. These people are not appreciating how wonderful you are. and don't deserve to have you around. Staying in a situation like this, will only encourage resentment and anger. Therefore, you have a duty to yourself to consider ending it.
You will notice the 'lightness' you feel immediately when you don't have the attitude around you anymore. You deserve to be appreciated by everyone around you. We all do.
You will need to accept that not everyone will like you, or treat you right. That is their issue, not yours. They do not like themselves. If, though, you are putting up with their destructive behaviours, you don't like yourself either. Also, if you continue to expand your boundaries to accommodate others, they will continue to push them. You need to take a look at yourself and why you are allowing anyone around you that is not kind, loving and accepting.
So the lesson is... if you want people in your life that will love and respect you for who you are, you will have to do the same.
As for the people that are not appreciating you, they need to hit the road.