I am so sorry you are going through this..it is more than heartbreaking.
If you have not already done so, seek your own legal advise.
For your own financial safety, you may need to file for a legal separation or divorce.
Generally, half of the assets belong to you so listing someone else as a beneficiary only matters if he dies. If you get a settlement, all assets will be added up and generally you are entitled to half...what he does with the other assets, is his choice.
Because you have young children, he should also have to pay child support and also alimony payments for your support.
You might also be able to have yourself named as beneficiary on accounts and life insurance policy's, especially unti all the children are of legal age. Also, request that he covers your health insurance costs.
A legal separation allowed me to stay on his work health insurance...when he divorced me 9 years later (by a text message with no explaination) I lost health insurance coverage and it cost me $1200 a month to obtain coverage.
Start making a list of every expense that you and your household have. Haircuts, groceries, taxes...everything for at least 6 months. This can help determine how much money you are entitled to.
He does not have your best interest at heart as evidenced by listing another person as a beneficiary on his IRA....since he has taken that step, it is important that you protect the assets that are rightfully yours. I may not be correct but from what I understand, if he were to die she would received part of his IRA...so dividing things before he dies is extremely important.
I am very pro marriage and have been standing for a very long time. I was encouraged by my priest to file for a legal separation to protect myself..and he was 100% right. I never thought my husband would not be "fair" and it became very clear that he did not think I was entitled to anything other than half the assets we had both worked for and accumulated over 32 years.
I quit my job 7 times to move for his career and I was not employed when he had his MLC....it's horrible and sickening to have to do this...it is the "business" part of this mess that must be taken care of...your heart and how you feel about marriage doesn't change because you take legal steps to protect yourself.
We are here to support you. Ask many questions for people here have seen it all and will be able to give you some examples of what could happen if you leave things for him to take care of.
I am so sorry.