Having major surgeries and/or illnesses frequently alters people's self-concepts and parts of their identities in ways that can be disorienting. There is often a process of not only physical recovery, but also of redefinining "normal" in your life.
I think you could find a lot of comfort through talking to a therapist who specializes in Health Psychology as these are psychologists who are trained to work with people who have had major health problems that have then affected their mental health and identities. The psychologist could help you figure out not only what parts of your life and self have changed, but also what parts have remained the same- this can be enormously useful in constructing a new life for yourself, post-illness, that feels happy and productive. Learning to manage anxiety about your illnesses recurring is a big part of this work.
You might also find some support online through a support group- I would try looking on the American Heart Association website as a place to start- I'm guessing that they, or other health organizations like theirs- would be able to provide you with information about online support groups composed of others who have gone through similar medical challenges and are now facing depression and anxiety issues. Talking to and hearing from others about how to cope with these things might help you to feel less alone.