No, no, no and NO.
The old adage "do not invest more than you can afford to loose" exists for a reason.
If you cannot afford to lose it, you do not invest it, full stop, no argument.
You put the stuff you cannot afford to loose in a bank account, preferably more than one bank account with completely different companies.
You absolutely cannot and should not rely on your investments, whether in passive indexes or active investments.
Index funds can go down a lot, VERY QUICKLY and take a long time to come back, just look at the charts ! It can take a year or more for a big drop to return to a previous value. That's not a comfortable position to be if you can't afford to loose a large chunk of your money overnight.
Also, remember that index funds, even the passive ETF ones, are a structured product. Even a passive ETF could be temporarily gated due to liquidity constraints, unlikely maybe, but it could if the circumstances were right. And even if they don't gate in such circumstances, you could expect the tracking error to widen and hence further reducing the amount of money you get back from a sale in such circumstances.