Hi, I'd like to help you with your question.
I can understand how hurt you must be. It sounds like your husband's behavior came out of the blue and was a big change from what he was like with you. It is completely understandable that you would feel hurt and devastated.
When you mentioned that your husband's behavior changed after his heart attack, it made more sense. Often, when faced with a major life crisis, people will change, men in particular. They feel they are missing someone or they fear what happened to them so much they change everything in an attempt to control their lives. They feel this will distance them from what happened to them and everything will be fine.
Sometimes there is also a measure of self centered behavior involved. That is often the case with older men who feel they missed out on something and want to reclaim their youth and not face old age. They begin to move away from their old lives in a effort to find something new and different that will make them feel better. The focus is totally on themselves.
I understand this hurts you. Although it is a very common occurrence, that doesn't help your situation. Have you thought about trying some support groups? Or if you attend church, your pastor may be able to help you for little to no cost. Pastors are usually very versed in marital issues. You may also want to try the local community mental health center. They charge on a sliding scale only.
Why I mention continuing therapy is because right now, you need support. Try trusted friends and family as well. Go out, even if it's just to a bookstore, or for coffee with a friend. Pamper yourself as well. If money is an issue, try a simple manicure or even a new haircut. Your self esteem has taken a hit with your divorce and anything you can do to boost yourself up will go a long way to helping you recover.
There are also some books you can read to help. One is called He's History, You're Not: Surviving Divorce After 40 by Erica Manfred and Tina Tessina PhD. Another is Rebuilding: When Your Relationship Ends, 3rd Edition (Rebuilding Books; For Divorce and Beyond) by Bruce Fisher. You can find these at Amazon.com or your local library may have them as well.
Remember, this was not about you or anything you did, rather it was about your ex and his behavior. Keep reminding yourself of this, especially when you are feeling sad or upset about your divorce. You had no control over him, but you do over yourself. Believe in yourself and focus on repairing the damage and moving on the best you can.
I hope this helped you,