Don't panic.
Do millionaires panic over the occasional financial hiccup? You're millionaires. You shouldn't panic.
I have your net worth down as at least $1.4 million, plus the equity in your primary home. To most followers of this website, that's enough money for the entire family to declare financial independence and quit work. Yet, you plan on continuing working in a $100,000 per year job while living a very reasonable and thoughtful lifestyle. You're more than fine.
I calculate your annual income and expenses (assuming your husband loses his job and only collects $6,000 in unemployment for the year thereafter) showing a net cash flow deficit of $26,362.16 assuming you add $1,000 a month in health plan expenses to what you currently list and continue to pay your older son's college tuition. Interestingly, I have your retirement contributions in the same period at $25,654.00, meaning you are only $1,000 net negative, before implementing any cost savings.
Of course, with this budget you are in effect swinging from being healthy savers to barely making ends meet on your wage income -- but I wouldn't worry too much about that. The point of having $1.4 million in liquid net worth is to allow yourselves to slow down at some point and start living off dividend income instead of wage income. At the very least, further savings at this point is optional -- your retirement is very well funded, with $1.4 million of investments in the bank plus (if I read your post correctly) a healthy defined-benefit pension which becomes available in a few years plus (I am assuming here) some amount of social security entitlement on your husband's earnings history down the road (which, if you both are in good health, should probably be delayed until age 70).
Others have pointed out specific areas where you can probably save money on your regular spending, and I generally endorse them; however, I would review your insurance policies and needs carefully before cancelling them. The premiums are not onerous, and once you are in your 50s it can be difficult to re-qualify for life and disability insurance if you realize a year from now that you'd rather carry more. Even though you have ample savings and no truly critical dependents (i.e. young children who can't fend for themselves), the death or disability of one spouse can still impose burdens: the survivor might end up having to outsource more domestic labor (yard work; meal preparation; driving; etc.), and there are still mortgages and college tuitions to consider.
I would also phone up the college's financial aid office and ask about how to re-file in light of your husband's impending job loss. There may be more scholarship money on the table next academic year, or at least some federal student loans (a portion of which ought to be subsidized, meaning the government waives the interest charges while the student remains in higher education). I don't think you need to cut off all assistance to your son, given your comfortable financial position, but it is more than reasonable to ask him to step up his game and borrow federal loans while you cut back in light of the circumstances.
Assuming you can save $10,000 per year in cash flow (between cutting household expenses and your older son getting more financial aid / student loans), you'll be about $15,000 cash flow negative per year in your cash accounts. Which is fine. You have $17,000 in cash, $110,000 in taxable brokerage accounts which would cost you, at most, capital gains taxes to access, and $55,000 in Roth IRA accounts -- which allow you to pull out principal (but not earnings) tax and penalty free (you tell me how much of that is principal). You could easily sustain 10+ years of negative $15,000 annual cash flow without triggering a single taxable withdrawal from a retirement account.
Plus, you can pull money out of regular IRA accounts penalty free (but the withdrawal is still considered taxable income) for educational expenses of immediate family members. Plus you can set up 72t SEPP withdrawals on various of your retirement accounts to get more money out penalty free (again, the withdrawals will likely count as taxable income). Plus you are not far away from age 59.5, when you can just take money out of your retirement accounts when and as you wish, the way God intended them to be used. So there is zero reason to panic over the idea that you have a big pile of money out there but you just can't gain access to it. The truth is, you have plenty of money that you can get to very easily.
Here is how I cut your numbers:
Annually Income & Expenses:
$96,356.00 Salary
$3,710.00 Side job
$6,000.00 Spouse salary / unempl.
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$106,066.00 Gross Annual Income
-$1,396.00 Medicare tax
-$13,078.00 Fed income tax
-$4,030.00 State income tax
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$87,562.00 After Tax Income
-$988.00 Life insurance
-$910.00 Disability insurance
-$12,000.00 Health insurance
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$73,664.00 After Insurance Income
-$15,600.00 401k contribution
-$7,696.00 Ret MST 8%
-$1,326.00 Rest MST 30K
-$1,032.00 State teacher's fund
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$48,010.00 Take Home Pay
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Annual Living Expense Monthly
$5,729.16 Mortgage escrow (TI) $477.43
$240.00 Add'l home ins. $20.00
$480.00 Gym $40.00
$462.00 Add'l life ins. $38.50
$720.00 Instrument rental $60.00
$95.88 Hulu $7.99
$480.00 Landline phone $40.00
$1,920.00 Electricity + internet $160.00
$638.28 Add'l disability insurance $53.19
$612.00 Life insurance (spouse) $51.00
$600.00 HELOC repayments $50.00
$2,400.00 College savings contrib. $200.00
$2,964.00 Automobile maint. + ins. $247.00
$1,440.00 Automobile fuel $120.00
$12,000.00 Misc. $1,000.00
$4,248.00 Automobile payment $354.00
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$35,029.32 Reg living exp. ex. mort. $2,919.11
$9,342.84 Mortgage (PI) $778.57
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$44,372.16 Regular living expenses $3,697.68
$30,000.00 College tuition $2,500.00
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$74,372.16 Total living expenses $6,197.68
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-$26,362.16 Net cash flow
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Balance sheet:
$479,510.00 Spouse 403B
$18,206.00 Spouse IRA
$10,228.00 Spouse taxable
$181,388.00 Spouse rollover IRA
$26,978.00 Spouse Roth IRA
$42,574.00 Spouse TSA
$18,019.00 Rollover IRA
$28,097.00 Roth IRA
$503,367.00 403B
$17,736.00 Checking
$99,289.00 Taxable - inherited
-$10,000.00 HELOC
-$135,000.00 Home mortgage
$135,000.00 Home value (at least - add'l equity not included)
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$1,415,392.00 Net Worth