Taxes or exchange tips

[Adrian Cartis]

I am selling my STR for $250,000.
2022 Purchase price $180,000.
$130,000 current mortgage loan balance (Interest only, never refinanced).
I used $50,000 of my own money (my HELOC).
Does IRS tax me for $120,000 ($250k minus 130K), or real gain of $70k ($250k-$180k)?
I know there will be commission + closing cost + depreciation in the equation, I just tried to keep it simple.

Also, with the numbers from above, I think it makes sense to do a 1031 exchange, invest in a new property and save quite some money.
The profit ($120K or $70K) will be taxed at 20% or more, up to 37%, correct?
I am not a RE professional, I have a full time job ($100k/yr on w2), so I'm thinking I'll pay a lot of money for taxes next year if I don't plan this transaction properly.

Thank you in advance for taking the time to read this, and maybe give me some professional recommendations.