I don’t know what to do here.

I (20M) was dating my girlfriend (22F) of 2 years and she just recently left me for something I did 9 months ago when I was drunk that she knew about since the day after it happened. I texted my ex girlfriend (21F) of 4 years that I missed her and loved her. She had reached out to me in the past and so did I so I told her if I ever did again to text my current girlfriend and tell her I did. I got really trashed one night and texted her not recalling I did until the next morning, my ex was currently with someone and he was pissed I had texted her. Fast forward to the present my current girlfriend(22F) finally said she couldn’t forgive me and left. Whilst my ex (21F) reached out to me that she is pregnant but her boyfriend cheated on her and didn’t want the baby at all. She is currently talking to me saying she misses and loves me and wishes I hadn’t gotten with that girl and waited a few more months for us to both come around and get back together. I need help in this decision. Should I remain single for around half a year and let her focus on the baby so we could try things again or just focus on myself and not date for a while. Me and my 22F girlfriend lived together for 2 years so it’s tough being alone