Is it normal to have thoughts

i dated girl in my early teens and we had a son in our late teens . in our early 20s she grew bored with been settled so young and start going out more with friends she met someone as she said more exciting and we split up she moved on and had another kid the more exciting life didnt last to long with the new cat turning into a abuser i done ok in life and always looked after my son and her and other kid in whatever way i could . i built up a carreer and yet i datted but nothing serious . till about 10 years later i met someone and 1st time i fell in love . but at same time i got bad time off my son about me seeing someone and deserting him which id never do . it caused problems with girl i was datting in the meantime my mother died and i was at a very low point . ii slept with my sons mother and not only the once and soon she told me she was pregnant . we had another son and we married and now 14 years later i honestly cant understand how it happened and im here now . i love her as mother of my 2kids but im not in love with her i use to love life now i hate it when i look back i loved that girl and stopped seeing her so my oldest son wasnt hurt .my oldest son doesnt even speak to me cause i wouldnt loan him large amount of money i often lie in bed asking myself how did this all happen