Answer
As salamu ‘alaykum to you too my dear child.
You do indeed have a soft heart, and you have every right to try and protect it, but you would not be protecting it by behaving as they do. Getting hurt is just one of those things that help us to become better people as we grow in self understanding, and therefore understanding of others.
Once your heart goes cold, it is like not exercising the muscles in your leg, and finding out one day as you get up, that you can not walk, or that you can walk very little. By keeping the heart open we learn to be honest with ourselves, and not only that, we also are able to receive and give love, which is very important in a marital relationship.
My dear child, you are in your mid-teens, hence you are going through emotional ups and downs.
This makes you vulnerable to the words of other, particularly when your emotional developmen very much yearns to belong, to be considered, and to be appreciated. You are more a social being than a cognitive one at the moment, so therefore you are going through an emotional, and psychological change. Because of this, you are volatile, and as you have admitted, you are partly to blame. This means that you are going through changes in perception of reality, and so you are bound to be sensitive more than normal.
Your mothers reaction to what is going on, indicates that she considers the two sisters concerned to be in the wrong in terms of how they are treating you, and you feel that you do not deserve the treament that you are getting. In between the two, is the balance, which may not seem apparent to you, but is trying to find its way. For instance, look at your older sister, who says on the one hand that she willl do nothing for you, and then on the other hand, she does wonderful things for you.
It might seem contradictory to you, but all it says is that regardless of how she feels sometimes, you are still her sister. You just have to be patient and give it some time, and your mother’s suggestion about giving them some space, is a good idea. Give them a chance to get over what happened, and do not spoil you resolve to not throw hurtful words back, because then you know what will happen about giving them some space, is a good idea. Give them a chance to get over what happened, and do not spoil you resolve to not throw hurtful words back, because then you know what will happen then!
On guiding the nafs, Sheikh Fadhlalla Haeri tells us:
“One set of ayat in the Qur`an relates to the nafs guiding itself, with Allah’s permission, towards right action. These verses show us that guidance comes from within. “And there are signs within your souls” (Qur`an 21:51). God tells us that no nafs experiences faith and trust except by God’s decree, that is, by His permission and design. There is another ayat that states: ‘Say that you are not the originator of any good or bad(outcomes) for yourselves’ (Qur`an 7:188). In other words, everything comes to us from Allah; we merely filter it through to ourselves, with the option that we accept it or reject it as an experience.
In another verse we are shown the inner technology to cope with what we are given in this world” As for your younger sister, she is young, just like you, and may hold grudges for a while, but as she too will change, so will her expressed feeling towards you change. Next time a hurtful word is said, just let them know in a considerate way, that their words hurt you, but you forgive them; or just ask them, what was it like when they were your age? I know it all seems hard on you, and you think that the current situation will never change, but time will put this all behind you, so why not begin now, by being the sister that you want them to be.