What's going on with my cherry blossom and how can I fix it or prevent from continuing?

It could be a frost crack. Is it on the south/west side of the tree?

Frost cracks form when the sun shines on the tree trunk in winter, warming the center of the tree. When the temperature drops, the bark cools faster then the inside of the tree, forcing the tree to split. It happens more often in thin barked trees (like cherries) and is usually not noticed until spring.

The good news is this is an old split. The rolls of bark are the trees attempt to heal itself. The second and third photos are of the below graft part of the tree (the lower trunk attached to the roots). Its growing suckers - keep them pruned off.

Thanks for your response. Yes it's South west facing. Glad to know it's old. Is there anything I can do this winter to protect it?
Anything I can do to help heal it or stop the suckers?

There's not much you can do about the weather and nothing to do once a crack has formed. Keep the suckers pruned as close to the bark as possible.

There's no way to stop suckers from forming. I have a 50+ year old Magnolia tree and I'm cutting them off multiple times every summer. You just keep after them and cut them off when you see them as Lucy68 said. They're a drain on the tree's resources, so the sooner you get rid of them, the better.