What should I do ?

About a week ago I walked in in my husband with another woman and I don’t know if I should leave it’s the first time he’s done this that I know of we’ve been together ten years and married for five we are expecting a baby next month so I just don’t know what to do should I forgive him I love him so much and I don’t want to raise a baby alone what should I do ? I never thought he would hurt me this bad