It is a difficult one and I don't have the answers either. I don't know when there comes a time to contact T or when you sit through the need without giving in. I guess you can only go by instinct and by what you know your T is okay with. If over time you feel the contact is only making you need him more than perhaps it's time to re-evaluate.
Like Perna said above, often it's a matter of sitting it out and waiting until you feel better. Emotions pass, like most illnesses. But that doesn't mean not reaching out for support because sometimes that is necessary. I don't know how you can tell when that point is reached, short of being in crisis. Battling with it myself today so I'm sorry I can't be of more help