I have and still do put up with a lot of things that I wouldnt if it wasnt for the fear of being alone, never finding someone who wont judge me and just plain low self esteem.
On the outside I can come across as this hard *** dont take no **** from no one type. Truth is I take tons of **** from the people Im in a relationship with. Cross me as a friend and I will hold a grudge and not talk to you for months or years but not when it comes to partners.

Dysfunction is also all I know so having an unhealthy relationship is "normal" in my world.
It feels better for me to have someone even if they mistreat me. The glimpses of "comfort" and the physical stuff pacifies me enough.
I can totally relate to your son
I think that knowing your self worth and feeling secure "alone" is a big component to this.