If you're young, sell now. Then take some time and pursue something more recreational for a while. When you're ready to get back into the grind you'll still have a nice stake to start with.
I might even argue even if you're old, sell now still. I assume "a ridiculously small team" means 3-4 people. Even assuming an equal split (it sounds like OP is CEO/main founder, so should be even more), that's $3mil a person at least. After tax that's still $1.5mil. It allows OP to live a much improved life, while at the same time optionally pursuing more business ventures if they wanted, or simply spend more time with family and kids.
Why would the tax be 50% ?
OP did not specify their country; some countries tax that high.