How can I prove it's a scam?

Hi scammedonlyonce and thank you for letting us know this scammer is still active. I am sorry to hear you were scammed. It is hard to face that information and you can see you are not the only one that falls prey to a professional liar.
If you could post any pictures you have received and emails or chat logs, it could help someone else stop this from happening to them. Sometimes scammers revisit an old successful story or pass the idea along to another one. They had no right to do this to you. You were only reaching out to connect with someone. They are criminals out to steal your heart purely for the interest in making sure they steal your money.

Thankyou for the update, Scammedonceonly.
Yes, once found out, the tricksters lay low for a while but will usually pop up again after the heats gone, But happy to say this scam artist has been mentioned in the forum and anybody conducting an internet search will be drawn to the previous comments. It will save someone in future. And a warm welcome to the forums.