Personally i don't think Selyse's last minute change of heart should change how we see her, she has been hating on that certain character* from day one even with the change of heart it was her fault..
Well when I say she earned some respect I feel like I should point out it wasn't a lot. lol
I'll try to explain myself a little bit I suppose. Now, before this event happened and she had her 'change of heart' moment, I kind of thought of her as a bland 'I'm a religious zealot, bluarg" character with no really fleshing out.
But, after watching that scene I stopped and had a moment of realization. I'm a person who has worked, studied, and read on "Relationship Science" (Yes, it's a thing) and I recall reading an article (You'll have to forgive me, as I don't have the article at hand to share as a reference) that discussed how women seem to take upon more traits shared with a man after sleeping with them, and the more men they sleep with, the more varying traits they receive will be (which caused the commen saying "Bitches be crazy") which will become more relevant as I go on later.
Keeping that in mind, we have seen that in GoT, as well as our own real world history, that they value female virginity as far as weddings go. IF you're not a virgin, you're not getting married, or you're considered married to whomever took your virginity. we've seen this as far as the many marriages that Margery has had in the past, since they have used the fact that her virginity was intact to allow her to marry first Joffery, then Tommen. So, using this knowledge of their society Selyse was most likely a virgin upon Marrying Stannis.
Now, as we have all scene both in the show, and even the book (I'm in the 600pg range of the 'Game of Thrones' book) Stannis is very dutiful to his position, often times making choices he wouldn't on a moral ground but as his duty he would and should. Now, what I'm about to say would paint the picture that I should approve of Stannis' actions, but I still don't.
But time and time again we see how Selyse talks about how she failed in her duty to give Stannis sons, How she was so quick to embrace her new religion (As it's her position to do so in most cultures), how she kept talking about the various things he should do to achieve his goals, being very supportive to him all the way and trying to be his guide but at a lesser extent of what Mel is doing. So, it's very clear she's dutiful as well (Which may be traits, as aforementioned, that she received from years of marriage) and she would be eager to stand by her husband's side.
Now, while all of this was part of my appiphany two days after writing this post, here is what really made me feel for her. With her new religion, Mel constantly talks about how the power of kings can do anything (To paraphrase) and how it's so powerful. We've seen this in how she "milked" stannis for his Kingly essence, how she (Mel) wanted to burn Gendry, and how she even tried to sleep with Jon Snow.
Now, we put all of this together, what do we get. It's pretty safe to assume that Selyse (Who has mentioned doing this before) had gone to Mel for council, which is comment to see that faithful people will often seek out the priests of their faith for council and advice, and, as she seems likely to do, Mel told her how powerful the Kings blood is, what she can do with it and she probably threw in something like, "The lord of Light wants you to do *Blank*" so, went and did whatever she was told to do, and talked Stannis into following Mel's orders because she knew better and it eventually lead to this.
To catch up all of what I"m trying to say is, "Selyse is just a wife, trying to be the best wife that she can because it's her "duty" to be a good wife, as it's her husband's duty to, at least try to, become king. In her attempts to do so, she kept talking to Stannis about how right Mel was in all things and what not, in an attempt to council her husband, like a "good" wife should do.... even at the end, she kept trying to be dutiful to what Stannis wanted, trying to see reason, to convince herself that it was for the greater good.
But then you see it.... a break in her duty.... a break in her shield where the dutiful zealous wife cracks and the mother reveals itself, where she screams, "I can't do this," and rushes to save her child... the only child she had been able to breath life into... to give a name to, to raise, to love and to mother.
That's why I respect the woman more than I did. I cannot say I love her as a person, but there is a respect where she was just nothing to me, outside of a minor character there for plot development sake.