It's great to see you making concrete plans to protect yourself. Don't stop with the bank account, please. More important is your health.
About the ego stroking rationale for sexting, for a moment. Yes, you're right. Infidelity does occur, quite often, as a quest for the ego stroke. But think about how a junkie functions: first, s/he uses just a little bit, and gets the expected high. Then, a little more is needed to get the same high. Eventually, life centers on finding the high, and the need for drug, in higher amounts and strengths, increases. The drug may---and often does--change, in the quest for that high.
It's VERY likely that after 10 years of sexting, your husband is using it not to gain the high of the ego stroke, but to set up the event that will provide the REAL high. It's very likely that he has escalated out of the texting realm.
I'm sorry. I wish this were not true. But it's very uncommon for a person with poor boundaries to draw a decade-long firm boundary around physical infidelity. If he's made the graphic texting okay in his mind, it's not a huge leap to make other things okay in his mind. I truly hope I am wrong, but because the stakes are high, it's important to consider the possibility.
I can't begin to count how many of us have spouses who "only texted," or "only flirted," or "just called 900 numbers," or even "just watched porn" (which is not always problematic, but for a subset does replace emotional and/or physical intimacy and cause real problems for them, and in their relationships).
I can't tell you how many of those spouses, the ones who "just" watched, or "just" listened, or "just" <fill in the blank>, have, in fact, escalated to have physical affairs. Frighteningly, they often escalate to have high-risk sex with high-risk partners.
We don't want you to learn this about your husband. We especially don't want you to learn it the way some of us have: with the diagnosis of an STD.
It's for that reason that I recommend that you take measures to protect yourself. At this point, you do not know the extent of your husband's behaviors. Because of that, you must assume he is like any stranger you'd meet. Would you have unprotected sex with a new man in your life? No.
Well, right now, the man you live with is a stranger. As heart-wrenching as it is, the truth of the matter is that you know no more about his sexual history than you'd know about any random guy you'd meet in bar. (I am so sorry for typing this---literally, I have tears in my eyes; the hardest thing for me to assimilate, post-d-day was that I did not know my husband. I truly, truly hope you discover that you DO know the truth, and can move forward from there. But for now, you cannot make that assumption. The risk is too high.)
You must be tested for STDs. In your shoes, I would not have sex with him until he, too, was tested and the first round of tests came back clear. Then, until the recommended re-tests (which might be spread over 24 months, depending on your doctor's recommendations) are completed, I'd use a condom for every sex act, including oral sex. (I will spare you details of the STD I contracted; suffice it to say it was in my oropharynx, and was next to impossible to diagnose and treat---and caused me over a year of real suffering. I will say this: oral sex without condom is not safe, if your partner has been with others whose sexual histories you do not know.)
Only then, and ONLY if, by that time, you are convinced that NOTHING NEW -- no sexting, no anything--- has taken place, would I resume unprotected sex. I would resign myself to the possibility that, in this marriage with this man, you will never achieve that certainty. He's remorseless, and he's continued the same bad behavior for which he VERY recently expressed "remorse" and offered hollow promises. He's in DEEP, and he's making no real gestures to stop.
I am so, so sorry to belabor these points. I do so only so that you stay safe as you work to heal from this. I genuinely hope that you are able to move forward in the way you'd like to, and that there are no other discoveries to be made.
Know that, if there are, you WILL get through it. You have lots of support, and lots of strength.