I am 25 now and have 2 dc of my own. When I was only 10 my dad suddenly left us, me and mum had our suspicions that it was this younger girl he worked with although he denied it. He moved in with friends into a house share, (I mean who leaves their family for a house share in their 30's, tragic.) Mum wanted him back, we all did. so after a few months he did agree to come back at one point but it was obvious to everyone he did not want to be there and this only lasted a few weeks until he upped and left again. This time for good. Weeks after, he finally admitted to Mum he had a girlfriend and low and behold it was this younger girl who we are pretty sure he would have been seeing the whole time. After this I used to see him most weekends for about a year but eventually I told him he would have to choose between having me in his life or his girlfriend, he chose his girlfriend. So I refused to see him anymore. They were engaged in about a year at the most then had a new daughter only 2 years after he left us (I mean wtf who even does that), and got married shortly after. Mum said it was literally as soon as their divorce came through, disgusting.
My "dad" is still married to OW and has two girls one is 13 and one is 8. and also OWs son who is now 16 so what a nice happy family. I used to look at their social media all the time, OW's and the older kids. But now I have them all blocked as it makes me too angry. He used to pay child support until I started work and emails me every so often, and sends me money for my DC birthdays and my birthday and Christmas. I did tell him when I was pregnant and when my LOs were born and I sometimes ask him for money (😳 ) but I don't want anything else off him.
DH thinks I should at least talk to him as I never got his side of things, he had similar with his dad and after a difficult few years reconciled a few years ago, now they are best mates. But his dad did not betray his family by having a brand new set of kids, he is with the same lady but never married. I just think too much water has gone under the bridge though and especially now I am a mum I will never understand how anyone could leave their own kids. But what if I regret it one day?