Welcome to the community!
I understand your current situation. However, there isn't a way to just stop paying until you get back. That said, Fido does offer a temporary suspension for a reduced fee on eligible lines. Are you currently under contract? If so, do you have an older subsidised plan or one of the newer financed payment plans? Unfortunately, subsidised plans are not eligible for the temporary suspension as the cost of phones is incorporated into the plan cost. If you have a financed plan, you should note that the temporary suspension only applies to your services. You would still need to pay the monthly costs for financing the device.
Unfortunately, there is no way to add the temporary suspension online. If you're eligible for the temporary suspension, you would need to contact customer service to have it set up. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
If a temporary suspension of your line does not suit your needs, you might need to cancel your services. You should note that in doing so, you would lose your current plan and phone number. Upon your return, you would not be able to retrieve either. You should also note that if you are currently under contract, you would be required to pay-off the balance of your device. Again, you would need to contact customer service in order to cancel your services.
If you wished to keep your phone number, there are various ways one can park your phone number, though those ways would likely also require a fee of some sort. You should also note that upon your return, it's unlikely that you'd be able to get back your current plan. You would need to select an in-market plan when you return.
Hope this helps 😀