When you are that ill during pregnancy, and NOTHING is working, abortion can seem like a silver lining. So, feeling happy is not wrong. I would not call what you are feeling "happy", I would call it relief. You should not feel horrible. Some pregnancies are really rough on one's body. Your next pregnancy could be easy as cake, but this one is killing you. Not literally, of course, but you know what I mean. Being in school, being literally drained of all your nutrients (be it the fetus draining you or your stomach draining itself via vomiting), yeah I can see how an abortion at this point would relieve you and make you feel better, even happy. Abortion comes with all sorts of feelings, and all of these feelings are normal. It doesn't help that you have all sorts of hormones raging either. If abortion is what is best for you, then go for it. Just be sure to think it completely through so that when you look back on things, instead of feeling regret, you know you had a valid reason.
If you for some reason change your mind about your abortion, morning sickness more often than not, goes away around the fourth month. But for some people, it stays up until birth. I don't say this to convince you to abort or to even stay pregnant, I am telling you this so that you know. There is no way of telling if you are one of the ones who has a rough first few months or if you are one of the ones that is going to go through vomit hell the rest of your pregnancy. If the misery and sickness you are going through right now would be put at ease by abortion, then go for it. Regardless of your emotions, you have to do what is best for you. Good luck!