Distant and uninvolved partner

My SO has been distant from the very beginning of this pregnancy. He even had an affair with a coworker in the first weeks, which is now over. He is a good father to our 2.5 year-old daughter and he claims that he wants to make the relationship work, but he isn't making any extra efforts to communicate or to be present so I feel so alone. We have started couples therapy and I hope it can help us work things out. I am at 13 weeks now and afraid to be a single mother of 2 at 40, but will do it if I have to. Any insights?