An abusive ex had a stroke
Thank you for submitting a great question - one that many people may ask when this type of situation arises, but are often afraid to explore.
First of all, I am proud of you for taking care of your own mental health by choosing to have removed yourself from an abusive, long-term relationship. It takes a lot of courage and self-respect to finally claim your right to live life without abuse.
However, the guilt, as you pointed out, can really cloud our judgment because we have already invested so much time and effort into trying to make a bad relationship better. So when we see our ex going through a major medical issue like you described, and suddenly in a vulnerable position needing help, the instinct is to feel obligated to help.
It may be helpful to consider that the guilt feelings were probably instinctual before he had a stroke, and even throughout the relationship. It is usually guilt (along with other emotions) that keep us feeling trapped in an abusive relationship. We feel guilty about everything - about our own shortcomings, about thinking about leaving, about what we might have done to deserve such treatment, about what other people will think of us if we stay or go, etc.
The preexisting propensity to feel guilty even though it may fly in the face of logic, is probably what makes it so hard, now that he needs help now that the tables have turned and you empowered yourself to get away from his control, and now you have the control to decide whether or not to assist. It is hard to feel feelings that come with being in a new or different position that are unfamiliar to us, so the mind naturally wants to talk us into going back towards the familiar.
Throw in all the "shoulds" and "oughts" and the moral/value judgments we are prone to consider ("is it wrong to not help someone in need?" "does that make me a bad person?" etc.), and it turns into quite the conundrum!
Finding some structure to help organize the thoughts and feelings might be best, in getting past the guilt. If you were to make a list of all the reasons that it's better to maintain distance despite his circumstances, what would be on that list?
It might contain ideas such as that you left him for good reasons (like self-preservation) that have nothing to do with his health condition. That to help him would put you right back in the line of fire again and would prevent you from being able to get on with the business of healing from all the previous abuse, and remembering that there are others out there who can help him, that it needn't be you. That he can be resourceful and figure it out just like anyone else struggling with a new health condition, that you probably have tried to wear the cape one too many times for him and wound up depleted and hurt. You undoubtedly already know how that ends.
Another thing to understand about guilt is that it usually arises out of a belief that we have hurt someone, and that we "owe" them something more. That you left him, is the hurt - but you have to follow that premise with WHY you left him: because he was abusive in multiple ways over multiple years.
Lastly, some say that in situations like this, someone wanting to help is less about actually helping the other person as an act of compassion, and perhaps more as an act designed to lessen their own guilt so they feel better about themselves. We have ways of making gifts of compassion sometimes, all about us, if we're honest. So you'll want to examine your reasons for feeling guilty, a little deeper.
Equipping yourself with the positive, rational facts that you know to be in your best interest, remembering the reasons you left, trusting that as an adult he can and will find the help he needs and surrounding yourself with supportive people who can help with those reality checks we all need in these situations, might address some of the guilt and conflicting feelings.
I hope this was helpful, Kish, and I wish you the best of luck in this new chapter of wellness!