At times there's simply too much emotional turmoil and pain to comprehend as the 19-year Kostyuk, who was born in Kyiv, reflects on the impact of Russia's invasion on her country and her fellow Ukrainian players.
"Right now is something indescribable, I would say, because there is a parent of one tennis player that died," Kostyuk told CNN Sport. "There is one tennis player's house that is completely destroyed," she said.
Kostyuk's own mental health has been affected as well.
"It was extremely difficult, the first week or two," she told CNN in a telephone interview earlier this month.
"It's been two months and you know, it's up and down, it changes. I'm trying to guide myself a little bit, just trying to see where I'm at. Trying to feel myself and trying to figure myself out," she added.
Kostyuk is extremely conscious of the importance of trying to manage her feelings and says she's been working with a psychologist.
"I started a couple of weeks ago, which helps me enormously. But you know, sometimes it goes to a certain extent that it's scary, the thoughts that come to you," added Kostyuk.
"I don't want to say the words because you know, you can figure out what I'm trying to speak about.
"Because at that point, there's so many things going on, you need to carry so much all at once that you are just like, I can't handle this anymore.
"I'm just like, what's the point where it's all going? It's never ending like what should I do with my life now? What am I living for?" she said.
'I shouldn't be silent'
What has helped Kostyuk and given her purpose is trying to educate people about the war in Ukraine.
"Everyone is doing this differently, but the only goal that I have is not to feel as if I'm a victim in this situation," she said.
"Because I'm not and I'm not positioning myself like this. For the first two weeks [of the invasion], I had this feeling that I'm a victim, like, I don't know what I should do because I rarely feel like this in my life.
"And this was the turning point for me when I changed this mindset of not being a victim," she said.
"I shouldn't be silent. I should say what I think. I shouldn't scream at the top of my lungs, like, please help us. We specifically say what we need help with.
"I'm still a tennis player, and I still want to compete. I don't want to get injured. I don't want to go to this to certain points where I'm just, 'you know what? I'm done.' I cannot play tennis at this point ... I cannot do anything."
Kostyuk is one of several Ukrainian players who have called on Russian and Belarusian athletes to denounce the Russian government's decision to invade Ukraine if they want to compete in international competitions.
Earlier this month Wimbledon organizers announced that Russian and Belarusian players will not be allowed to compete at this year's edition following Russia's invasion of Ukraine.
Twenty-time grand slam champion Serbian Novak Djokovic criticized the decision to ban Russian and Belarusian players from competing at Wimbledon this year, calling the move "crazy."
Meanwhile, Russian tennis star Andrey Rublev said that the ban is "illogical" and amounts to "complete discrimination."
In a media conference on Tuesday, Ian Hewitt, who is chairman of the All England Lawn Tennis Club (AELTC), which runs Wimbledon, said: "It is not discrimination in the form that is being said, it is a considered view reached as to what is the right and responsible decision in all circumstances."
In a Twitter post earlier in April, Kostyuk said: "As athletes we live a life in the public eye and therefore have an enormous responsibility. .. In times of crisis, silence means agreeing with what is happening."
As well as Kostyuk, Ukrainian players Elina Svitolina and Sergiy Stakhovsky are among those calling on the WTA, ITF and ATP to ask players with those two nationalities to condemn the invasion.
'Inside the tour, we're alone'
Kostyuk told CNN that critics of her stance have argued that "tennis players ... have nothing to do with politics."
"I don't understand, what's the point of dividing these two things? It's one big system that we're circling in. One cannot live without the other, and vice versa," she said.
"So for me [the idea that] 'sport is out of politics.' Honestly, for so many years, it's been proven completely the opposite," she said.
"We're trying to talk about the fact that none of the players have actually come up and spoken to us to try to help somehow," she said.
"We used to be friends with a lot of players. I'm not friends with anyone anymore, like one single player," she said.
"We know the whole world is trying to support us [Ukraine]. Everyone knows that what's going on is wrong. And yet inside the tour, we're alone," she said.
In response to Wimbledon's decision to ban Russian and Belarusian athletes from this year's tournament, the WTA distanced itself from the AELTC's decision.
"The WTA strongly condemns the actions that have been taken by Russia and its unprovoked invasion of Ukraine.
"We continue our humanitarian relief efforts to support Ukraine through Tennis Plays for Peace," the organization said in a statement, adding they were "very disappointed" in the decision of AELTC and the Lawn Tennis Association which also announced that it would ban Belarusian and Russian athletes from competing in their events.
"A fundamental principle of the WTA is that individual athletes may participate in professional tennis events based on merit and without any form of discrimination," they added.
The ATP took a similar position, saying the decision was "unfair and has