"According to the Christianity, God doesn't want us ..." Actually, yes, he does. God created all of his children with eternal life in mind. Anything less would be unfair and evil of him. He even calls Satan Perdition, for the inconsolable Loss he feels for him.
"... that's the reason He sent his only Son to die for our sins..." No, he sent his only BEGOTTEN son (we are all his children, of course, as the Bible endlessly states) to suffer an infinite punishment for sin before his arrest. His crucifixion was just a detail, but a necessary one, so he could resurrect himself (and all of us as well) into physical life, health, and immortality.
"... but why?" He loves us, dear one, because we're his children. But God can't accept us in our sins. He sent Christ to help us be purified of sin and come back to him safely.
"how does the God's love work with this?" Easily.
"I mean if God loves us but at the same time he condemns us to hell ..." We are only sent to hell in the hope of purifying us of the sins we could not or would not give up. But hell is never forever. Rev. 20:12-14 shows that death and hell must both be emptied and destroyed. God's love, justice, and mercy are all intact. There is only finite punishment for finite sin.
"...but by Jesus's grace we are saved of his anger,..." No, God isn't angry with us. He loves us and wants what is best for us. It's no credit to him to lose one of his children forever.
"... so Jesus loves me but his Father doesn't love me, ..." No, they both love you more than you know.
"I need to accept Jesus in order to please God?" No, you have to obey God and do your best to keep his current commandments, including doing good works to other people if you want to please God. I can't help it that so many Christians deny this. Jesus did say that he will reward us according to our works, not our beliefs or some nebulous "acceptance."
"how does work that Jesus die for me and for everybody?" Mostly so we can be resurrected into tangible, physical, life, health and immortality. No death, no resurrection. No resurrection, no immortality. No immortality, no eternal life in the third heaven. What Jesus did about our sins is mostly something else. Before his arrest, on a quiet night on the Mount of Olives, Jesus Christ suffered an infinite punishment for sin. It had to be infinite, or it couldn't have been applied to anybody but Jesus himself.