I got help from BTC Portugal (Portuguese slack channel, thank you @riclas, @shutaru and @malmen) and was able to solve this issue.
This is what I did (ETA: 10 minutes):
- Close all running Multibit HD wallets you have. I really mean all, no computer in this planet should be running your wallet at this moment.
- On a "new", clean computer, or in a Virtual Machine, install Multibit HD, a fresh installation.
- When the new Multibit HD installation asks you, instead of creating a new wallet, chose the restore wallet option.
- Insert your seed words and date.
- Voila! It will now take some minutes to synchronize your wallet with the chain, but it should load only the confirmed transactions.
- Go to the other computers, uninstall Multibit HD completely.
- Make sure you delete everything in folders such as
C:\Users\<user name here>\AppData\Roaming\MultiBitHD (or
/Users/<user name here>/Library/Application Support/MultiBitHD/ for OSX) or simply search for
MultiBitHD files on your disk and delete them all.
- Install the wallet once again in those computers and recover just like you did in steps 3 and 4.
If you are really in a rush, just perform steps 6, 7 and 8.
Don't do any of this if you don't know your words and date for recovery!
UPDATE: This doesn't actually solve the issue. In fact the wallet thinks that all your transactions are confirmed, until you try to spend the money. Then you'll get a
Low spendable balance detected. some of your bitcoins are tied up with ongoing transactions. error.
The thing is that the wallet refuses (or the network refuses) to double spend that money, because they see the unconfirmed requests already broadcasted.
For what I've read these requests will never timeout from the mempool. This is a known issue of BTC, and is making this coin hard to scale to the rising numbers of transactions (as of now only 3 transactions are processed per minute, which is ridiculous).
The only way I can perceive now to "solve" these unconfirmed transactions, is to use accelerators.
These accelerators are basically mining pools (a huge team of miners), where you ask them "pretty please" to consider adding your transaction to their next created block. This will confirm your transactions. However, this solution is at very least, not accessible.
You can try asking it for free here: https://www.viabtc.com/tools/txaccelerator/
After I get my money back, I'll consider not using Multibit HD anymore, since issues like these made me lose some money so far...