Deleted messages

Hey guys, just a quick question. First a little backstory.
So I was over at my girlfriends house and I was messing around on her iPad taking some silly selfies and stuff. I went to check out the pictures in the camera roll and I found screenshots of her having intimate conversations with her ex a few days ago. She's clearly cheating on me based on what was said in these texts but I want to give her some time to come clean. So I decided to send these screenshots to my phone using her iMessage (I know, it's a little unethical). Because I wanted to have proof if I have to confront her on it.
So my question is, will she be able to know I sent those pictures to my phone if I deleted the iMessages? It's her only apple product and she didn't have a conversation started with me on her iPad.

These kinds of threads are tricky to respond to and I will only respond to the technical question at hand. Anyone else responding to this thread beyond the technical questions will have them deleted to avoid ethical/moral and other discussions which NEVER go well..

So, if you delete specific messages you've sent from iMessages they are removed from the device at that time. However, if the phone was backed up to the computer after these messages were sent, then a full restore could bring them back into view.

And, of course, the Apple servers knows about it, but there is no way of getting that back onto your phone..

Completely understand about answering only the technical question. I was really hoping that would just be the case. Thought it might be a sketchy question to ask if I didn't explain my situation first.

The messages were deleted between backups, so they definitely weren't backed up onto her iTunes or whatever, so a full restore won't bring them back right? The cloud doesn't save messages?

Backing up to iCloud depends on the settings of the device.

In my case, I have iMessages on my iPhone 5S and also Messages on my multiple Macs connected to the same Apple ID and so I can see all the messages I've sent from any of the devices. I just deleted one of the messages I had sent a while back on my phone and checked on Messages on my Mac and the message still remains. So previously sent things remain on connected devices and deletions don't have a global effect.

Since the iPad is her only device, its unlikely that this message would be visible elsewhere..

The bottom line is that unless she went to great lengths, she's unlikely to find the messages that were deleted from the device or even know that they were messages were deleted to begin with..