Sorry you're going through this, M2G. It seems like you know you shouldn't -- and I think your plan for what to do if you find yourself slipping (call current T or your mom) is great.

The urges can be terrible -- do you and your T talk about what is behind them? What is it you're hoping to get by contacting old T? Love? Sexual attraction? Attention? It might help more to actually address the urges by finding for yourself what it is you're looking for... just from a source that's going to be healthy for you.