You forget that Tom pretty much grew up in the Corleone household. Therefore, he was as close to Mike as a non-blood brother can be. Mike knew that Vito obviously held Tom in high esteem and Mike just as obviously respected his father's opinion. So, he did have some love and respect for Tom. But, as the novel clearly points out, Tom was faked out by the five families, a fake that, as the novel also points out, Genco would never have fallen for. Mike clearly held Tom in part responsible for Sonny's death. How could he not? A consigliere's job is to protect the family's interests and its people. By Sonny's death, Tom failed to do that. It's one thing to lose a capo or soldier. But, to lose a family member is another thing entirely. And he may have also blamed Tom in part for having fallen into the trap Hyman Roth set for him at the Senate hearing. Keep in mind that eventually Mike turns on Tom when he tells him that he can take his family and his mistress and leave the Corleones. Remember that?