❓ASK – What happens when my transaction gets rejected in Blaockchain? | Proxies-free

I did a mistake one day ago. I was trying to send a payment but I did a mistake there. I customized the network fee too low that’s why my transaction get remain “Unconfirmed”. I sure it’s going to be rejected. My question is, what will happen now? Will I get back my BTC in my wallet again? If yes, how long it may take to get back again? Or I have lost that forever?