How do Hamlet's actions at the grave support the depth of his feelings for Ophelia?

While in the cemetery, Hamlet notices a procession and burial that seems less elaborate than usual, signifying that the deceased was a suicide. He and Horatio stand aside while Laertes argues with the priest about the paltriness of the burial rites. In the course of his arguing with the priest, Laertes reveals to Hamlet that the dead body is that of Ophelia. Gertrude steps forward to say farewell to Ophelia. Laertes follows. In his intense grief, Laertes leaps into his sister’s grave to hold her body again and orders the gravediggers to bury him alive. Provoked by this show of grief, Hamlet then reveals himself. After grappling with Laertes, Hamlet declares that he loved Ophelia more than forty thousand brothers could. The king and queen dismiss his avowal as madness.