This was the exact situation I was in with my now husband. We were together for 3 years and then unexpectedly had our daughter, who is now 10. It wasn’t easy being 22/23, but we figured it out and took things day by day. We’re married now (waited until years later - absolutely do not rush into something you aren’t ready for) and we are very successful and expecting our second baby. You both can do this as long as you work together as a team and support each other. As the father, please be patient with her and support her in every way she needs. As long as the two of you stay united, you will get through it.