Hi, I'd like to help you with your question.
It sounds like this man has moved on. If he felt that your relationship was still viable, he would wait for you. But he has reconnected to his high school sweetheart and her children, which probably means they at least share a good friendship if not more.
The other clue is his refusal to discuss this relationship with you. He may just not want to face the truth of how he feels about her or he is moving on and doesn't want you to know so rather than lie he avoids the subject.
Either way, this does not look good for your relationship with him. The best way to get answers is to confront him, tell him what you suspect, and let him know you are considering moving on based on what he has told you so far. Ask for an explanation at least so you know how to react. But unless he comes right out and says he still wants to be with you, any other response most likely means he does not intend to wait for you.
If it ends up that you end this relationship, allow yourself time to mourn. It is a loss and you need to allow yourself time to work it out. You will probably feel a variety of feelings, including the urge to convince him to change his mind. But try to find support the best you can from other sources. A clean break is much easier to move on from than one that keeps opening wounds because of additional contact.
I hope this has helped you,