I experience thoughts just like this. I have a loving husband and a wonderful 7 year old son. And yet I cannot help but think of "how, when, why and what with" most of the time. It makes me feel selfish and self absorbed too, but it also makes me realise I am seeking release and peace.
I hate these thoughts and their presence in my life. They have pushed me to two attempts already, which I regret!!

I understand how you feel. You are not selfish at all. We can have all the common sense and logic in the world but they simply do not work when our hearts and minds are besieged with feelings and thoughts beyond our control.

I'm am still new and not well known to the various forums but from what I have seen, there is never a need to apologise for being in a certain place. I hope that you will feel some comfort from that. Take care of yourself.