Well, I have read that there a lot of brokers and i will recommend you from the one i have read OANDA, eToro etc. I would suggest you IronFX the broker i am currently trade with but is up to you who you trust and if you have any experience with any of them.
Hi cabumbo, hope you are continue doing well. You can search there are a lot of brokers promising for no negative balances such as fxpro, fxprimus, oanda, ironfx, and so on. You choose the one you would like to trade with.
I’m confused how you could lose more money than your deposit.
Every place I’ve looked at opening account will automatically close out your position if you go below the requirement needed to maintain the leverage.
Obviously you shouldn’t make a single trade that maxes out your entire deposit. But for most purposes, aren’t you protected by the minimum requirement to make a trade?
The swiss national bank stopping the euro peg is an example how you can end up owing your broker money. Its what they call a black swan event. Another way is if you have an open position on friday on sunday when the market reopens sometimes there can be a big gap and if that goes against you it might wipe out your account and then some but normally that could only happen if your using high leverage. In my opinion finance in general is like walking on a tight-rope and the forex market is know for being especially risky but on the plus side extremely lucrative.
Honestly, I have never heard about IronFX. I’d stick with Etoro or Oanda though since those brokers are tested over time already. 
For sure what is known is a better bet, but google them and check if you can withdraw!