Does the uke get raped or sexually assaulted by another man than the seme?

Almost, but nope

He doesn't get raped but assulted. Nothing too hectic compared to other yaoi

So what happened exactly? Did the other guy forced a kiss? Push him down and trying to go further? Sexual touching?

It's a huge spoiler to tell you the whole context of the situation, but I don't remember there being any kisses. The dude was going straight for the rape, but got stopped right on time.

At least it was stopped, but it’s so annoying that the authors always use *lets rape him* scenario ._. Especially when in most of these stories, having a gay relationship is super bad but the bad guys always go straight for rape...

I agree with you, but the scene in this story isn't as absurd as in other yaoi. It makes sense with the context and the whole situation