It could be codependency talking?
I think it's ok to reach out and extend words of kindness with your ex's mom's illness. At the same time the talk of rushing in to move closer to him and 'love' seem a bit out of place considering how poorly he treated you. Hence my writing that it could be the codepency(which is common in toxic relationships) talking.
When I think of codependency as I learned of it ages ago it's a need to rescue/nurture/save at the detriment to ones own peace of mind. To become utterly absorbed and enmeshed.