Husbands with another woman

I don’t know where to post this so please bare with me.

My husband and I have been married 10 years but have been separated for 2 years now. I still live in house with my daughter and our 2 boys. He pays for my car & sends me money for the children every Friday; $300.

When me and my husband separated it was me who chose it and I got an apartment and I recently moved back into the house a month ago.

Hes been working out of town for about 3 years now.

He came to pick up the boys 2 weekends ago & when they came home I heard about “daddy’s new gf” and my youngest would talking to his dad on the phone asking “where’s that lady” “can I talk to that lady” saying he loved her as well.

We had been talking about getting a divorce but knowing that he has someone living with him while we’re still married, I want an attorney.

What should I do?