Dammit! FO warned you for exactly this no? Ok. You did well to break the silence and start the talking. It not really wrong to unveil some of your emotions either, but you need be careful about it. Since you interpreting own emotions still, you extra vulnerable.
Frigid Onanoko see it this way: You brought over the message of nono. He kissed you anyway. Whatever - you can brush it aside as a mistake - you made your point and fulfilled your duty to communicate. You think you need to discuss anything else with him? Like what? You are in charge also, so its your fault also for the kiss (that is, in social terms, which is the level on which you interact with your brother. In reality he abused your vulnerability.)
An apology from him therefore is the cavallier thing to do, but you cannot demand it from him. Perhaps you want to discuss how relation between you two should now go? Perhaps you can ask your older, stronger, handsome, loving brother to please not kiss you and not touch you... "oh please, brother, don't! not there!" (humbly apologize for trying to make risk disgustingly obvious.)
Do you understand the risk?
This is what Frigid Onanoko meant by 'assaulting,' although granted, choice of word was awkward because assault is an act of aggression whereas your brother is acting out of weakness. Nonetheless, the effect on you is the same. FO implore you, please please value your own feelings above your brothers'. Instead of discussing with your brother 'where this is heading'/ 'how are we going to resolve this'/ bla bla, why not set the rules on your own? You can, you can do that.
It may be a bit of a struggle though, a struggle against yourself at least and perhaps your brother too. Against your desire to not let your brother down, against your sense of guilt perhaps - can you think of others? Against your brother, and FO (such a doomthinker!) sketch worst situation where your brother corner you in your own room to 'demonstrate the extent of his affection,' you need to be prepared for that. Perhaps you think your brother will never do such things... But do you really want to give him a platform to actually prove he wont? Better to just close the door on that possibility.
Dont let yourself be put off, don't subordinate your actions to the demands of your brother, don't subjugate yourself to his sorrow, his desires. Above all don't think you can get support from your brother. You may ask it, he may offer it, but it will be worthless, in fact he will gain from it, which is here your loss. Struggle through this and push through this fight. The big reason why you not inform your parents about this is to protect him, right? This is your weapon, a threat. You need the proper way to handle this weapon. Describing here:
The threat is a commitment to tell on your brother. If you are unable to make a credible commitment, the threat is void. Therefore you need to set an example beforehand. Repeating the 'hitting' argument from before. Threaten to hit him if he gets too close. Be a bitch. Hopefully he won't stress it but if he does, make sure to be aggressive (He no respect your demands wtf!!!) Now if you threaten him with telling on him, he has adequate reason to believe you have the balls to do it. This strategy much more effective than whipping out the gun that really hurts, immediately, before even demonstrating you can actually aim and shoot. Every time you fail to validate your threat, your opponent feels strengthened and you feel weakened. This game is simple. It has just started. There are three relevant outcomes:
(in next post continued)