After looking at your profile I see you're only 23 years old. That means you broke up with this guy when you were 19 and if you learned about him cheating two years in you were 17.
The sad truth is teenage romance is never going to be replicated as an adult. You will have gathered some wisdom from being hurt and disappointed. Only during that "first love" are people naïve and "all in" emotionally and physically.
As we mature/get older we learn to carve out a place for ourselves.
No longer are we living under our parents roof. As adults we have responsibilities which include demanding jobs, rent/mortgage, car note, utility bills, and countless other appointments to attend to. We learn to "compartmentalize" dating, love, and relationships. It will never again be "all consuming" as it was in your teenage years.
You now understand that no one is "perfect". You're comparing these new guys to your idealism of something which was not true!
After all you discovered the guy was a liar, a cheater, and had a child. Those are not exactly traits you should be pursuing!
If this guy was also your first lover you're going to feel a natural bond. However the reality is as you get older ideally you learn to love smarter. You combine your mind with your heart when choosing.
Unfortunately the "smarter" we become the less "fool hardy" and romantic we become. We learn to detect "red flags" early on.
When you're 30, 40, or maybe have teenage children of your own you will realize just how unrealistic it was for you to have believed you had found your "soul-mate" during your teenage years.
In order to "move on" you have to want to "let go".
Most people who can't move on don't really want to let go.
Focus more on why you broke up instead of "romanticizing the past".
In order for your ex to have been "the one" he would have had to see (you) as being "the one". People who are "in love" don't cheat.
He may have loved you and cared about you but he wasn't "in love" with you. He wouldn't have cheated or risked losing you if he thought you were all that "special".
“I don’t miss him, I miss who I thought he was.” – unknown