I've been avoiding a lot of things that remind me of my ex and I'm starting to think it's unhealthy.
What exactly are you avoiding?
Sometimes I avoid visiting the mall, because it reminds me of being in a relationship
It is understandable to have the mall remind you of your relationship. Just understand that avoiding these things is never going to solve the problem. Try to do things that make you feel better, and gain the strength to overcome these stressors.
I should stop following my heart.
You should follow your heart. Just because it did not work out this time, doesn't mean it won't the next. Seek help getting over her if you need it so you can move on in life.