Big hugs dear sis @damselindistress big big hugs..
Take a deep breath and let's peel the layers of your situation back. Before doing so, I want to remind you that it's okay to be upset, it's okay to feel sad, it's okay to feel frustrated, empty, hopeless. Be kind to yourself. And one thing I can be certain of regardless of which path you choose is that THIS, too, shall pass.
I'm in no way an expert in your situation sis since I'm not even a fly in the wall in your life but I'll try to help. Whatever you decide in the end, it will be the best decision and I can assure you that.
A few questions for practicality: what type of sponsorship is he waiting for? Is it green card petition from his family in the US? If so, yes matagal nga yun. Is it worth it for me? It depends but let me ask you: what do you think will happen when his petition is approved? He would fly to the US already? What would happen to you then will you join him? How about your status in the US? You can't stay in the US if you have a tourist visa lang. Even if you enter the US as a tourist and marry him in the US, you still won't get legalized status immediate. As he would be a green card holder, he can not petition you easily kasi priority is fiance or spouse of American citizens. If I'm not mistaken, a few years ago, 7 years ang average waiting time for spouses of green card holders. And that was before the current administration (Trump). The current administration is stricter now and if anything would make it more difficult for immigrants. This is a fact.
So my question is, are you willing to live separately from him even if ikasal kayo sa US? If he married you here after his petition is approved, ganun rin he still can't take you with him. My point is there seems to be a lot of humps down the road and it will take a huge commitment and planning on both of you if you want to work it out and pass the humps together.
That was the practical stuff assuming everything will turn out in a positive direction. Let's now see the other side of it sis...
You are only in control of one person in this equation sis, and that is you. You can't keep guessing what he thinks or what he feels. It will drive you crazy and if your assumptions are wrong, you might actually be unknowingly creating a rift between the two of you.
If I were in your shoes, what would I do? I'd think about it long and hard (and it sounds like you already have done that). I'll determine all possible outcomes. Right now there are only two possible outcomes: you guys will get married by hook or by crook, or you guys separate in the future whether because he does not really have future plans with you, or because he is going to the US and won't be going through that difficult process with you. We know the outcome is only one of two things. Now it is up to you to find out.
Knowing there are two outcomes, I will hope for the best but expect the worst. I will start by lining up my guns. Mobilizing and ensuring my support system is available, around me, and can support me if I will go through a period of mourning. I will also make sure I'm ready to move out -- have a place to stay, my finances are stable, and a regular routine to keep me sane, on track and not wallow in depression. Because sis, any type of loss is definitely a painful process.
What's next? I will open my heart and tell him my fears and my desires. Basically giving him an ultimatum in soft words. "I love you and wish to spend forever with you, but if this is not what you want and we can't move on to the next chapter, then I will set you free."
If he wants you he will come back, and will determine and drive his own future, not await the mercy of his fate from a visa petition. If he chooses a different path, then you would have cut your losses sooner and freed yourself from this situation. Win-win para sayo to confront (in kind ways) this situation.
Get ready sis, gather yourself and face this. You still have time to take charge of your situation and control the direction of your life. As I said, this too shall pass.
Ang haba na nito but honestly, ramdam ko what you're going through. If you need to vent, some strength, or bounce ideas off to, post here or send me a PM

all ears!
You got this sis. It seems like a blind leap of faith but have more faith in yourself and it's better to control your destiny than wait on the unknown... Love yourself more than let fear takeover you.