I was in a similar situation to you. My mother has some pretty bad heart problems and was diagnosed with hypertrophic cardiomyopathy. I debated for a while about getting checked out for it and did a fair bit of reading because I realised that it could have a massive impact on my life. I ended up getting checked out because I figured that if I knew that I had it, or was liable to get it, then I could adapt what I did. Everything that I read pointed to the fact that it shouldn’t stop me doing anything that I was likely to be doing (I’m not away to take part in triathlons or anything anyway!).
Some links that I saved at the time might be of interest:
https://www.cardiosmart.org/News-and-Events/2013/05/Patients-with-Hypertrophic-Cardiomyopathy-Place-Unnecessary-Restrictions-on-Exercise
http://www.cardiomyopathy.org/hypertrophic-cardiomyopathy/exercise-in-hypertrophic-cardiomyopathy-hcm
In the end I was lucky and my mum didn’t have the gene that meant that it could be passed on to me. You should be offered genetic counselling and genetic testing to identify if this gene is something that you have and is likely to be passed on to your sons. Maybe also get in touch with the British Heart Foundation – they must have some sort of support group, even if only online. I’m happy to share thoughts and experiences too, just email.