Three possibilities: if you're overwhelmed and want everyone to be helpful, you could keep the money where it is, at TIAA. TIAA will be happy you're keeping your money there. I don't have much experience with them.
Another is Fidelity, where you already have an account. Fidelity has low cost mutual funds (by that I mean under 0.25% annual expense ratio), so you would pick a "total stock market" or "U.S. market" fund for your retirement account. Fidelity will want to help you, but TIAA won't be that enthusiastic since they're losing your money. You'll have all your money in one place, which is simpler and easier.
Finally, you can compare all three: Fidelity, Schwab and Vanguard. For a complete novice starting out, I'd recommend Vanguard. Vanguard has all low-cost funds (low expense ratio), so you won't make a bad choice. Schwab and Fidelity have good and bad choices, so you need to be more careful there. So if having 2 accounts isn't an issue, and you're a complete novice, I'd go with Vanguard. But that assumes you're okay with having Fidelity and Vanguard accounts.
If your stress level is overwhelming, you could keep the money at TIAA for the simplest resolution with TIAA people being helpful - and someone else in this thread can walk you through what they did.
If your stress level is fine, and you're more worried about bad investments, I'd suggest Vanguard. I can't resist a small joke that will hopefully be taken well: maybe you also want to be "divorced" from the company where your husband has his assets? :)
By the way, I suggest "low expense ratio" funds for two reasons: they save you money, and they tend to beat other funds. But low expenses mean no advertising budget. But take this SPIVA report on fund performance: for the past 3-5 years, the S&P 500 (the 500 biggest U.S. companies) beat ~75% of "active" funds. Over 10-15 years, the S&P 500 beat ~90% of "active" funds.
https://us.spindices.com/documents/spiva/spiva-us-mid-year-2018.pdfLow cost funds don't spend money trying to beat the market, and as a result their performance is better. It's hard to beat the market every time you spend money trying to do so. So I'd suggest a low-cost index fund for the money, at Vanguard / Fidelity / TIAA per your decision / stress level.