Heroine gets cheated on, and ends up with ex husband's best friend

[Mihaela]

H1 and H2 were best friends. They fell in love with the same girl, heroine (i think her name was Ellie but i'm not sure). She marries H1, who was a teacher, and after a few years while they try to have a baby, ge cheats and his mistress gets pregnant. Heroine also is pregnant, but he either doesn't know or refuses to believe it. She ends up with H2, and they got married and have a daughter too. H1 dissappears for a few years and comes back later and is upset that his son is so close to H2, even closer than to his mom. He ends up with a single mom whose daughter was in his class. Can anyone help? I think one of them was named Matt.

I read it a few years ago, i think it could've been published sometimes around 2015-2020??