I think the bawling your eyes out part is very dependent on what touches you, but I can recommend "Yours to claim" as a similar wealthy-poor dynamic (but it does start way more toxic, and personally for me, the second love interest's backstory made me cry uncontrollably); and a very similar story to Si-eon's traumatic past I would say is "The Insatiable Man" (similar - my mother who actually loved me messed up my life entirely - )
https://www.mangago.me/read-manga/release_your_persona/
https://www.mangago.me/read-manga/seven_sundays/
very emotional and romantic manhwas :)
Does anyone know a similar story like this? Preferably, the one that will make bawl my eyes out.