I'm going to offer an olive branch by offering a possible "fix" to rectify some of the major issues I see here.
We have the guy in contact with said girl over the years. They break up but they remain good friends, with her sharing information about her life to all her friends (MC included) about her (maybe) marriage, child, family life, etc. There's a break in communication for a short(ish) amount of time, ie to assume that there's problems occurring in her life, and THEN she shows up with daughter in tow at MC's home, saying "I'm really sorry but I have no where else to turn to". You offer help to your close friends, not people who you "knew" almost 20 years ago. Not perfect, but much better ease into at your cute slice of life manga.