How child support am I entitled to?Am I entitled to alimony if I been married for 23 years and how long?

How much child support you would get (assuming all three children are his) will depend not just on his income, but also on the cost of living where you live, how much money is required to care and provide for three children in that area, whether any of the children have disabilities, issues, developmental delays, etc. that make their care more expensive, etc. So we can not answer how much you would get, but only state that should you get primary custody of them, you *will* get child support.
Since you have been married for many years and he makes almost two-and-a-half times what you do--and so presumably pays much of the families support or cost of living--means that you will get alimony or spousal support, too. But since there are again many factors that go into determining this other than relative incomes and length of marriage, including the spouse's relative ages and health, how long each can expect to keep working, future earning potential and not just current income, we cannot say exactly what that amount would be.
To better understand what you would be entitled to, consult with a family or matrimonial law attorney who can take all the particulars of your situation into account and advise you. Remember, too, that you will also be entitled to a share of the family's assets (e.g. investments, bank accounts, real estate, vehicles, etc.).