Oh, I feel for you. My single daughter did the same thing. She and grandson were living in our guest house next door. We were literally co-parenting with her and all was going well. She met someone online and thought it was love. My husband and I literally grieved. We were so attached to our 7 year old grandson. Luckily, we can afford to fly him here as a unaccompanied minor for all major holidays and we fly to them about 3 times a year for a long weekend. It turns out that we have him about 9 weeks a year with Christmas break, fall break, spring break and 4 or 5 weeks in the summer. Maybe, she will let you have him on school breaks. Save your pennies and get him to you as often as possible. He will love to see you. As for the 18-month-old. It is going to be much harder to have that close bond and you will most likely have a more traditional long-distance relationship with that child. Those relationship are rewarding, but different then the super close ones. Again, My heart goes out to you and him. He is going to miss you so much and you will miss him too. Keep your relationship good with mom at all costs.