I totally agree @Powderfinger that the shame is on those that choose to abuse in any form.

Here is the dichotomy however - can we show others the path we want them to take and in doing so change them in some way while not giving them the same in return. I do not believe we as individuals should change for anyone - our true, authentic self has to be the one we present so we can be around, with, alongside those that share those same values and beliefs as we do. If someone we are with does not share those fundamantal things we so highly regard in ourselves then maybe they are not who we should be with anyway.

What you may see as 'helping' someone may infact be wanting to mould them into something they are not - as what they are fundamentally is not what you would like them to be. This is a generalisation here I am talking about and not specific to your present situation but unless someone wants to and/or has a desire to change no-one can do it for them.

I hold that love can be blind as we often fall for someone quickly without actually really knowing them. This comes with time and in that time we may find out things that we did not or could not see in the beginning when it is natural for both parties to want to please the other in any way they can. Once the 'honeymoon' period wears of and rela life gets in the way that is when the real person is shown - sometimes for the better, sometimes for the worse. We can close our eyes to the little things at first because we want things to work but the longer they go and the bigger they get, the harder it is to  accept.

When it comes down to it - we cannot change the essence of someone no matter what we do or don't do - that is their burden to carry and we can only hope that in the process we are not the ones that are immeasurably hurt. Unfortunately you have been - sooooo much but do not let go of that kind heart and empathy you have for people because it really does matter.