The manga I'm looking for has the protagonist reincarnate years into the future in his world. The story arc that I remember is that some adventurers are attacked by black humanoid ants. The protagonist and his friends/party go help the city or town that is near where the adventurers were attacked. For some reason that I can't remember the protagonist gets separated from his friends/party. His friends/party enter the anthill/hole and encounter the black humanoid ants and get overwhelmed by them. They are then saved by white humanoid ants who help them escape to their hideout in which they meet the Ant Queen. The Ant Queen tells them that all the black humanoid ants use to be white, but some black coat hooded man appeared near the ant's core and corrupted it along with most of the Ant Queen's colony. Hearing the Ant Queens story, the friends/party agree to help the Queen regain control of her colony. The protagonist somehow meets with the black coat hooded man. The man then reveals himself to be his childhood friend from before he reincarnated who held a grudge towards the protagonist who was always hailed as a genius and while he worked hard found that he could never surpass/defeat him. The childhood friend made a deal with a demon/devil for immortality and power in exchange for his soul so that he can meet the protagonist when he reincarnates and kill him. The protagonist and childhood friend fight with the protagonist coming out on top. As the childhood friend is dying the protagonist tells him he had already been defeated by him as the childhood friend had married their female childhood friend whom he was also in love with, hearing this the childhood friend dies.

Suterareta Tensei Kenja - Mamono no Mori de Saikyou no Daima Teikoku o Tsukuriageru

~4400 manga completed
~1700 ongoing...

Thats the one, thank you for quick reply.