So she should have risked, or even allowed, Connor to get them both killed over his own pride? That's insane. If that was his likely answer, that makes her choice to not tell him the correct one as it is the one that saves their lives.
That was her only goal, for them to survive and live in freedom together. Had she done nothing, they would have been tortured to death. If she'd told him her plan, his reaction would have gotten one or both of them killed if he did indeed respond as you theorize. There was thus only one way to get them out of the situation alive, and so she took it. People have a right to do what they have to in order to save their own lives and those of their loved ones.
The problem lies in the breach of trust. She did it behind his back and lied to him. She may have done it for a good reason, but as they say, "the road to hell is paved with good intentions." And in this case, Connor's loss of trust must have been enormous.
I'm sure he would have said no at first, but that doesn't mean she couldn't have convinced him it was the only way. Personally, I think Connor would have given in (not being a warrior, he clearly knew his chances were slim, so he would have surely chosen the lesser bad, though certainly not right away). But she chose to do it without consulting him; she could have framed it as something that would inevitably happen if they wanted to survive, or as an option, or whatever. But the fact is, she didn't do it at all.
Although it's true that there's a possibility that Connor, faced with such a prospect, would have killed her and then committed suicide (or that afterward he would fight in the arena knowing his chances of survival were slim, which was possibly like committing suicide).
The one responsible is Merrek. They were literally his prisoners, under such brutal conditions that death was inevitable unless they could find a way to escape. Without power to defy him, or survive the arena which was the only way out available to them, there was only one option and that was to appease their captor. She endured that hell for the sake of their lives and their future. You're blaming the rape victim for submitting instead of being killed for resisting.
I'm not going to take away his guilt, but he's already dead, so there's little revenge or justice left to be done.
As to the child, you are placing way too much weight on genetic lineage. The real father is the one who raises the child, who is loved by the child, who the child calls daddy. Do you know how many children are adopted as infants and never told until they're adults? Are adoptive parents any less parents to you? If so that's a very fucked up point of view... then again that is at least consistent with the rest of the twisted mindset you've displayed on this topic.
In fact, like adoptive parents, he has the right to choose. Adoptive parents don't have a child imposed on them because the state, the church, or some flying spaghetti entity wants them to; they choose it voluntarily. If you don't tell him, he doesn't have that right.