It would be best if you left your mistakes alone and suffered the consequences of not checking here first to see how you install a new lawn. You can spend a lot of money to try to fix it, but in the end, the crabgrass wins.

Take the rest of the season to practice good lawn care and, come the 1st of August, then start the process for reseeding. Spring seeding is a bad time because the grass roots do not develop enough to resist the summer heat and because the crabgrass is germinating at the same time. Seeding in the fall alleviates both issues. Then next year, if your seed took right, your grass will be healthy enough to resist both the heat and any crabgrass invasion.

Nuking it now is the worst of all possible worlds. You'll have zero turfgrass and 100% crabgrass. That is likely what you'll have anyway. Just relax and do your best. At least it is green.