My husband is minding a 'jacket'

I am very unhappy in my marriage of 20 years. My husband has
betrayed me by being responsible for another woman's child, which I am sure doesn't belong to him.
Each time I talk about him getting a DNA test done, he refuses as he doesn't want the woman to think he didn't trust her.
He claims he has dignity in supporting her as he was sleeping with her for years and he has never seen another man at her house.
Her ex has seen me and apologised for what he claims to be an unfortunate situation as he wasn't ready for any children of his own but had fathered her daughter.
Now my husband is supporting his child but this woman isn't short of anything, so she doesn't have to be in another relationship.
I have confronted my husband so many times, but he doesn't believe me whenever I tell him about what she is doing.
I have made attempts to confront her, but I was asked not to as I would get her fired and he would have to support her family and mine.
He is already drawing back on my house money to make sure his outside means are met.
Now he has taken up another woman where he works, but he warned her about my visit to him every day and that she must act as though she doesn't know him when I am around.

SLEEPING AROUND

His co-workers have advised me to get a divorce as his habit of sleeping around will put my health at risk.
I am in a job that can support my kids and I, but though I want to leave my husband, and have mentioned it to him several times, it's like something keeps holding me back.
I don't have any intimate relationship with him and it's hard for me to go out there as I am afraid, and don't trust the men who claim they love me and want me.
My body is calling.
What do I do? I feel like I am going to go crazy.