How long have you been depressed? Have you talked to a doctor about this, or seen a psychiatrist? People who cut are really, really, very depressed. I feel so sad for them. No one should ever hurt that much!
The good news is a psychiatrist doctor will understand, because this is common among the patients they treat, they immediately recognize it as a sign of deep depression, caused by a hormonal imbalance, and they have an array of medications they can try, one of which will likely be the one that works for you. Unfortunately there's no way of knowing which medication will be the one that works for you, you just have to try them all one by one. (This is the part that really sucks. You try a medication, it does nothing. You try another medication, it makes you feel a little different, but not really any better. Try another, it has some side effect. Try another, and another,... But eventually one day you try yet another, and soon you just somehow "know" you've found the right one, because you can just tell. It's as if you lived your whole life having the flu, and then you find the medication that cures the flu, and you start to feel well for the first time ever, and it's difficult to explain. It feels like not having the flu anymore. It's definitely worth the search.
As for the past sexual molestation. My experience is when I'm depressed, my brain starts thinking of every time in the past I've ever been depressed, which I think is the brain's natural way of searching for a solution. Brain thinks, "What did I do in the past when I felt like this?" and it brings up all these depressing memories, which really isn't helpful at all, and I know it isn't helpful, becauase I know why I'm depressed, it's because my body is out of whack, body chemistry is off, I need to get back on my medication which works. I feel fine when I'm taking my medication. I am truly "normal" and feel normal and fine. Only when I don't take my medication, then I start to get depressed after a few days, and it just gets worse and worse as the weeks go on without my medication. Start taking my medication again, it reverses that, and I slowly get better again, until I'm well.
So I'm guessing, and this is just a guess, I may be wrong, I'm sure it happened and was unpleasant at the time, and maybe even led to some confusion over sex. That confusion and uncertainty can be delt with by a good couselor. Any LMFT or psychologist (talk therapist). The part that doesn't fit is it happened a long time in the past.
It's the cutting and suicidal thoughts part that doesn't fit in with the sexual abuse. Plus the long time between. Plus teenage years is often when depression problems manifest. Cutting indicates serious depression that needs a psychiatrist (doctor). Fortunately there's definitely hope that you won't have to feel this way forever. Fix the body / brain chemical imbalance problem and the other problems either fade away or become manageable with a counselor. It may be something as simple as a low thyroid. Or it could be caused by a long term lingering stress. Often they just don't know what causes it. Important thing is they can cure it.
I don't want to diminish the trauma of past abuse. The two ways to deal with that are 1. Processing. Telling a counselor your story and being heard. Recalling the memory by telling the story actually rewrites the memory of the event, so if you're in a safe calm peaceful place and you recall the memory, it will be rewritten and remembered with less emotional trauma. The story becomes less significant, so you don't dwell on it so much. Then the other way is 2. Purposely stoop thinking about it. Problem is, recalling a memory reinforces the memory and makes it stronger. If it's a memory that you want to have fade away, you can do that by purposely forcing yourself to think of something else whenever that memory comes up. Switch to thinking of something else. That way instead of reinforcing the memory, the memory is allowed to fade away. Memories that are not recalled fade away.
My experience though is for me at least by far the most important turning point was finding the medication that worked for me which lifted my depression so I'm no longer suffering every moment of my life (which of course really sucked).
Best wishes. Sorry my reply is a bit lengthy and messy. I suggest see your regular doctor and ask if they can either try prescribing an antidepressant medication, or refer you to a psychiatrist. Some regular doctors nowadays will try prescribing antidepressant medication, or at least get you started on one while they work on finding a psychiatrist. Also feel free to shop around and try different psychiatrists. If you aren't comfortable with one, try a different one. They're all different people. You'll know when you find one you feel comfortable with. (Wish I was a psychiatrist so I could help people. But I'm not, I'm just a patient.) And don't worry these are all typical stories they hear every day, they definitely understand!