I'm pregnant and my husband is divorcing me for the other woman.

my husband (42m) has been having an affair with his co-worker (38f) for the past year. We have been married for about 13 years, and our marriage has been far from perfect. I found out about the affair about 1.5 months ago the week before my father passed away from cancer. I am also 4 months pregnant with his baby. I moved out the morning I found out, and 2 weeks later I found them in bed with each other in our apartment. That evening he tried to commit suicide because I was telling the OW that we had just had sex in that same bed 2 days ago, and I have text message conversations to prove it. He denied it to her, called me a liar, went outside and slit his arm open, almost dying. Thank God he didn't die, but now he has left me, filed for divorce and wants to be with the OW, who has also left her husband of 15 years, and they have 3 young daughters together. My husband says she is everything that I wasn't. I know this is crazy and everyone tells me to move on and get over it, but it is difficult because I still love him and want to work it out for the sake of us and our children. He says he's 100% sure about the divorce. We also have a 12 year old son.
She knows I'm pregnant with his baby, I find it so heartbreaking that another woman would do this to a woman. I could never hurt another woman especially one that was pregnant regardless of how much I loved him.
What should I do, do you think their relationship will last? They talk about eventually marrying each other. I am having the hardest time healing, and normally I am a very strong ambitious woman.