I can't believe the author is making her cry not because she can't have children but becau...

YESSS. 100% RIGHT.

I mean, she did say that she was terrible for not grieving about her lost child. The only reason why she was sad was because it was the only way she could’ve gotten the emperor’s love, in the past life. In the present, she, i guess, is mad at herself for feeling embarrassed instead of saddened to be infertile. I don’t know what to think about this actually. I mean, I’m not mad at the emperor anymore since he never did the things his past life did but I don’t know if I should be happy that they are going to end up together. But one thing is for sure and that’s I miss my boy Carsien and wish he was the ml

Did you even read the correctly?
She's angry at herself for thinking that her having children was only a way to get Ruve's attention, for not even being disappointed she can't have children. She's angry at herself because she didn't even love her child, she thought about her child as a way to fix their relationship. She's sad because no one comforted her like this in the past. She thought the only reason Ruve could love her was because she had his child. Ruve tells her that this isn't true so she's relieved.

Did you and I read the same chapter? In the latest chapter she REALIZES that she used the baby as a bargaining chip and feels immense remorse for someone she’ll never have (the baby and how she used it back then). You missed the point of her entire inner monologue.

sorry i haven’t read this one yet but in the recent chap 136 who’s the female who walked in with a baby? if you don’t mind me asking

She was one of the empress candidates but she ended up marrying carsein's (red hair) brother.

ohh okay

empress candidates? what does that mean

Woman who were picked to be the empress, there were a bunch of them and if ruve liked one he would marry her and then she would be the empress

ohhh, does he fool or like sleep around and stuff then?

No but it was kinda like a political thing. In the end, no one was chosen since some were disqualified or gave up their right as empress candidate

Let's quote the chapter, It might make it easier to understand.

- "I see, I might never bear a child, and that means I can't make him smile warmly like that" => Is it different from the first timeline? Both just mean "I wanted/want to please him". If it's treated as character development it's only because now she "only" want to please him and does not expect a reward in exchange. Way to say "You were wrong in the first timeline to feel entitled to be treated decently as any human being should be by your own husband and properly trying to carry out your duties as a Queen".

- "Everyone would have been happy" If she had the child in the first timeline. With a violent man who not only psychologically tortured her but was physically abusive too. A man who showed that he didn't care about the child at all. He literally made her kneel on the ground telling her he will never recognize the child as his. He was the one who caused the miscarriage an then didn't care to show sadness nor to go see how she was feeling. Not a good idea. So why is she the one taking the blame because she did not give birth? First Ruve is the root of everything for this specific part of her tragedy. When readers are accusing the author to completly brush aside the first timeline, it's because of scenes like that. First Ruve was not "just cold" and "neglectfull". He commited actual crimes and atrocities toward her. Tia's inner monologue thus make absolutly no sense at all.

- "Oh, right. I was such a cruel woman" "I coldy let my child go " => Were to start? First Ruve is the reason she had a miscarriage in the first place (we don't know if the poison would have make her miscarry after all) so he was the only responsible for that, not Tia. But she is taking all the blame. She also only ever talk about how "she" was "cold" and "cruel" for not feeling attached to an unborn child. Except, she was an abused tenager without support at all, overworked, depressed and then victim of postpartum blues and filled with rage toward Ruve and Ji-eun. Of course she did not! She was in the worst possible life that anyone can imagine, and as a 17 years old. She was going to be a "teenage mother" but still tried to properly take care of him and protect him the best she could. If she didn't care, it's not because she was cold but because she was never granted to possibilty to actually bound. Motherhood does not magically appear out of nowhere once the pregnancy start. It's gradual. Also, names are supposed to be choosen by both parents together for instance. You can't blame her for waiting to talk about it with the father. And after the miscarriage she tried very hard to not think about it. She was starting to grieve until she heard of Ji-eun's pregnancy and she started to felt that everyone was laughing at her and let resentment take it's roots.

- "I felt humiliated rather than saddened when I became infertile again" => Of course she did! Because she was humiliated in front of all the nobility who made sure to degrade her because of that. It's the people around her who made her feel like she was "incomplete" and a "half-woman" first. Her purpose was to avoid her fate, not to become someone else's wife and mother. She had absolutly no reason at this point of time to actually care. She wasn't even going to get married fo as far as she had planned. So why is she suddenly an horrible person to not feel sad about that?

All in all, the "she is finally realizing how awfull she was" agenda seem to be clearly victime- blaming. Not feeling saddened for being infertile is not a crime. Being feeling by resentment rather than grief was also very much understandable with her circonstancies. She was literally raised for birth to be an Empress, so of course she would act the part.
Seriously, any reasonable person in her place would have had the same kind of reactions.