It doesn't matter if you sent the snap to yourself or to someone else. If that snap is opened or it isn't saved, then the servers will automatically delete it. Once you open a message, it will be destroyed automatically. Snapchat doesn't provide any status about previous messages unless they're saved.
This is what Snapchat developers provide on their official support page regarding Snaps:
Snaps: Snapchat servers are designed to automatically delete Snaps
after they’ve been viewed by all recipients. Opened Snaps typically
cannot be retrieved from Snapchat's servers by anyone, for any reason.
Snapchat servers are designed to automatically delete unopened Snaps
after 30 days.