What happens to my 403b in bankruptcy (exempt)?

Nothing, unless it’s a really rare owner-only plan.  403b

Generally, retirement plans are protected or exempt from creditor collections and from bankruptcy trustees.  According to the IRS, a 403(b) plan is

A 403(b) plan (also called a tax-sheltered annuity or TSA plan) is a retirement plan offered by public schools and certain 501(c)(3) tax-exempt organizations.

It is very similar to a 401(k) plan, which is also exempt or protected in bankruptcy.

So, the short answer is that nothing happens to your retirement plan.  You can protect the whole thing in bankruptcy.