in 2019 my filing status was married filing joint with husband being the earner i stayed home with the kids , now we are separated and filing married filing separate , the kids have lived with me all year and im claiming them .... so when it asks if i want to use 2019 earned income can i rightfully enter the amount from our joint return even tho he actually earned it to use the lookback ??
No, you cannot claim the Earned Income Tax Credit with a filing status of "Married Filing Separately."
Here is a link with more information on the credit.
It depends because the lookback can affect your child tax credit as well as the earned income credit. You can claim the child tax credit when you are Married Filing Separately. To claim however, you do need to determine what your portion of your taxable income was in 2019 on your joint return.
if you live in a community property state, this calculation can become challenging because all income is divided equally. Please review this IRS publication regarding community property rules but most importantly, a list of the community property states that require this type of reporting.