Over training is really hard to diagnose solely w/ heart rate, since some people manifest w/ increased resting heart rate, while others can have decreased resting heart rate. Fatigue, irritability, and mood changes may be more reliable symptoms. A tendency to get sick can also be a feature. Rather than your appendicitis causing your training issues, your training may actually have precipitated your appendicitis.
You describe yourself as "addicted" to cycling. You should look a bit further into your exercise patterns and what drives you to exercise too hard too often. I also have had a problem with a tendency to over train, which I feel is related to a fairly compulsive desire to control my weight through exercise. I've had to get tough with myself and enforce the rest days. When I stick to a reasonable ride schedule I feel better and make progress in training-- it becomes reinforcing. As an older athlete you will need more rest, and you can't expect to maintain your highest levels of training year-round. Set some goals for when you want your training to peak, and follow those peaks with a rest period. Cross-training is also helpful.