Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
He might cry a lot. Deku is very emotional, and being cheated on would be a very painful experience for him. He could also get angry, which is rare for him, but this situation would be so unjust that he might not be able to hold it in. He'd probably start to question his self - worth too, thinking that there was something wrong with him that made his partner cheat.
Zoro could react in a rather gruff way. He might say something like 'Nami, are you out of your mind?' But deep down, he might be secretly flattered. After all, Nami is an important person in his life. He'll probably need some time to process this unexpected turn of events and think about what it means for their relationship, both as nakama and potentially something more.
Deku might be initially shocked. He's used to Bakugou's aggression, but an actual injury is different. He could be in pain and disbelief at first. Then, he might try to downplay it, especially if he doesn't want to cause trouble for Bakugou, because Deku is generally a very forgiving character.
Well, some might be really amazed. They could see a new side of Deku that they never knew before. His singing might show a different level of confidence or a hidden talent, so they would probably cheer him on.
Some characters might try to understand Deku's motives. Kirishima, who was close to Bakugou, would be angry at first but might also try to find out if there were any extenuating circumstances. However, many would be afraid of Deku, seeing him as a threat now that he has killed one of their own.
Uraraka would be heartbroken. She was one of Deku's closest friends. She might lose some of her usual cheerfulness and become more focused on finding out who or what was responsible for his death. She could also struggle with her own self - confidence in using her quirk, as Deku was always an inspiration to her.
Luffy would be over the moon. He loves new adventures and a new baby on the ship would be like a new kind of adventure for him. He'd probably want to play with the baby all the time. Sanji would be a bit jealous at first because he has a crush on Nami, but then he'd also be really happy for them and cook all kinds of delicious food for the new mother and baby. Usopp would be making up all kinds of tall tales about the baby's future, like how the baby will be the greatest pirate ever.
Bakugo would likely be furious. He'd feel betrayed and would probably be the first to attack Deku, yelling at him about how he's thrown away everything they've worked for. Uraraka might be more empathetic. She'd try to understand what drove Deku to become a villain and hope there's a way to bring him back to the side of good.
The crew's reaction would be mixed with shock and joy. Franky would start building baby - friendly gadgets and cribs for them. Brook would be playing soothing music for Robin and Zoro to keep them relaxed. At first, some of the crew might be worried about how this would affect their adventures. But overall, they would come together. For example, Zoro's tough - guy image might change a bit, and the crew would tease him good - naturedly. Robin, being the more reserved one, might be a bit embarrassed by all the attention at first, but she would appreciate the love and care from the crew.