First I want to say I am so sorry that you are forced to deal with this. I would never ever wish rape/abuse on anyone. Second, I am so glad you realize that you need help--something I struggled with for a LONG time.now, Im not sure what you're personal experience is but I can tell you a little but about mine. I was raped and abused right after my 17th birthday by a dance teacher of mine. I struggled so much because she had groomed me for about 4 years prior to the point where i believed everything she said. she turned me against my parents and my best friends in order to make my life about her. anyways--I went through a lot of therapy once i finally got out of the situation. and i have to say, some days SUCK! I have a few people to turn to that have been there before, one being a high school personal safety teacher and one is the leader of the women's center where i go to school. i think the best advice i have gotten from both of them is that you have to feel what you are going to feel. its a process. one of them has been "free" for almost 20 years now and she still has days where she can not function. yes it gets "better" but don't be hard on yourself if you cant completely brush it off... unfortunately its something that will be with you for the rest of your life.
about remembering less-- i have points of time where i don't remember anything that happened (my junior year in high school) the only thing i can be sure of really was the abuse/rape itself the details of my life are completely gone from my memory for that time period. i don't know if thats what you're talking about or not.
dealing with sadness is a tough one. like i said you have to feel what you feel don't ignore it it will only make it worse. i try to tell myself how strong i am. I know you are strong too! tell yourself that DONT EVER FORGET IT! you have been through a horrific experience but you are still living life, yes some things are different, but you don't deserve to have your happiness and self worth taken away from you because of someone else's negligent actions.I know how hard it is to hear that "everything will be okay" when you're in a place that feels like hell. what i do to help is every morning when i wake up i think of one thing that i am thankful for or happy about. then i let that overshadow any other negative thoughts of the day. could be things like thankful for a friend of family member, education, a job, even things like having the laundry done. for the rest of the day anything bad you can counter act with "its okay, because at least i have my laundry done." stupid little things like that that provide you with self encouragement can help especially when you feel like no one else can relate to where you are in the moment.
best of luck!
STAY STRONG!