I'm not going to pretend that I know how you feel and I sure as hell won't tell you that everything gets better, I used to, but the fact is that I don't know if it will. I can hope that you'll get through this and feel joy again some time in your life but that's about it.
From all of that, what I heard; your son is very attached to you. Probably looks up to you in ways that only he understands. A daughter who's strong will still crumble from losing her parent, that can't be helped. A daughter who no longer speaks to her father (I'm pretty much that one), still loves him so much but can't get passed something. I crave that oppertunity so much and I still have it available. I've recently made small efforts to get there. We don't have anything more than small talk but after everything that happened, I still want a relationship with my dad. I still feel like a part of me needs him. When it comes to your wife, honestly, I can't figure that out; it honestly upsets me that someone who's your partner in life refuses to be even slightly intimate. There are people who still care for you and kids, especially your son (from what I gather). That's something. If you need someone to talk to, I'm here. I know it's online and not 100% human interaction, which is what us humans desperately rely on to survive, but it's something.
I can't tell you not to give up. Only you can decide for yourself if that's your chosen path. It's up to no one else. Just don't leave this world thinking that you don't have any positive impact on anyone's life. Trust me, even the most vile people have at least one positive impact on someone. Don't leave thinking that no one will miss you, that no one loves you. I didn't say this to try and sway you in any way. I said this so that if you do go, maybe you can with some peace or if you stay, maybe you can keep that in mind to keep you going. Either one depending on how you look at it.