Sorry to hear that. I was in a similar situation two weeks ago, sent an on-chain transaction with low transaction fees that got stuck. Luckily, a self-transaction from a change address (address where the change went from the stuck transaction) to itself but with higher fees helped in my case. It worked this way because the transactions have to be ordered on blockchain, so the miners, seeing higher fees, “processed” the stuck transaction too. Not sure whether this solution works in general or I was just lucky.