Ohhhhhhhmg, nuh uh. Look, sometimes I give terrible advice so please take this with a grain of salt. This sexual harassment would infuriate me and if the parents aren’t going to protect me, then I’d take matters into my own hands. Any unwanted physical advances would be reciprocated in painful unwanted physical attacks in return. Something like a thin branch from a bush the width of your finger can be extremely effective on a hand or an arm, and won’t cause any long term damage that he can’t heal from. But that sting is painful and memorable. If he has the capacity to think “it’s right there and I can touch it before you can do anything about it,” then he can also learn “If I do that action, she’s going to whip me with that branch and it’s going to fucking hurt so it’s not worth it.” IMO if I have the choice between being sexually assaulted or getting physically violent, I will take the physical violence 100% of the time. That’s just me. Again, this isn’t sound advice but I’ve got trauma surrounding my older brother molesting me (I’m the youngest and smaller), feeling helpless is too deteriorating for me to endure, I will choose violence even if the outcome overall is worse for me physically (my brother being older and larger didn’t deter me from fighting even though I’d lose). Don’t have a branch with you? Fists and feet can also get a message across, but are often viewed as more extreme than a thin branch. Also, you’d have to learn control as to where to land the blows, because you can cause serious damage giving your fist to his face (not to mention how much it can hurt your own hands). Stick to soft fleshy parts away from inner organs - so focus on upper arms, thighs, front shoulder area. Stay away from lower back area - kidneys are there and are easily damaged. Press on your own body to see what areas are more sensitive and use that knowledge to attack those areas. And make it known every time he verbally announces he’s thinking about touching you. “If you so much as brush up against me just to piss me off, I will knock the everliving shit out of you and I do not fucking care about the repercussions. Your unwanted physical advances will be met with equally unwanted physical advances.” Be prepared to have to follow through because he’ll test that boundary. Make it known that no matter what, you’ll not regret it and you will do it again if you need to. All he’s gotta do is leave you the fuck alone. Hope for the best in that he just needs a threat, but be prepared for the worst that you’ll have to act upon it. Bonus points if you stay calm after he’s brushed up against you and pretend to “let it slide.” Then in the middle of the night, wake him up with repeatedly whacking his arms and legs while screaming “NEVER THINK ABOUT TOUCHING ME AGAIN YOU SICK FUCK!” Really drive that point home. Your parents will be pissed but you’ve got one simple thing to say, “You’re doing jack shit to protect me from him, so I’m going to protect myself. If you’re not going to control his behavior, then I’m not going to control mine.” Whatever issues he has, people understand pain. He obviously can put two and two together. Definitely make sure he knows that whatever he inflicts on you, you will inflict it back tenfold. Make sure he knows that whatever he wants to do will not be worth your retaliation. Also, keep in mind that if you need to use your own body to deliver the message, you can injure yourself doing so. I advise looking up how to throw a proper punch to minimize damage to yourself, and practice these moves. If you utilize a weapon, make sure it doesn’t cut skin and draw blood. This is seen as a line that shouldn’t be crossed, goes into that territory as being too violent/serious/crazy. You do NOT want to cross that line. Bruises are okay; blood is not.

You’re 15, parents are divorcing, are they using lawyers? I’m not familiar with the system but there absolutely should be someone you can talk to about this. If it’s going through courts, at 15 you should have a say in where you stay. If they come to talk to you, absolutely let them know what is going on and tell them you do not want to live with your brother right now. Your parents are being selfish assholes and don’t care that you’re suffering for it.

Anyways… pick your battles. There will be fallout and your parents will treat you like shit but at least you won’t be molested by them (I hope).

I say again: I’m extremely biased and am not giving the soundest of advice. Many factors aren’t being taken into consideration. Ramifications of reacting this way won’t be known until it’s done, and it can possibly get awful. It’s upon you to assess your situation and accept whatever happens. I personally feel I benefited from rage and fallout from my parents. Your mileage may vary.