I'm sorry you feel so upset and hopeless, but seriously try to look at the positive side...you still have a lot of options and things to try that could help you! And if it makes you feel better, I started out with my IBS-C feeling bloating and in pain all the freakin time! I could only go to the bathroom like once a week on my own I too wouldn't have sex with my boyfriend(now ex) because I was in pain and felt so uncomfortable. And I couldn't digest many things well, barely any insoluble fiber. BUT...now I'm doing SO much better!! I can eat most things (except still am intolerent to whole wheat) and I'm ok, and I can go to the bathroom everyday, or almost everyday So you know what, that shows that people can improve with their IBS. Just gotta find the right stuff to use, and be patient with it. Everyone's different though, so what might work for some may not work for others.
I think the best thing to do is to start off with a stool softener(Colace or store brand equivilent, but NOT Peri-Colace) and start with a small dose of soluble fiber supplement. Keep in mind that often people will respond well to certain fibers and not so well to others, so if you start one and it gives you attacks, don't give up, you may just need to switch to another. Personally I took Metamucil and it helped me a ton, though I could not tolerate the other brands of fiber, but I think usually it's the opposite. If a stool softener and fiber aren't working and you've been on them for awhile, then I'd say progress on towards Miralax. But try over the counter stuff first. Personally, Miralax gave me bad attacks and I was unable to use it. But most people can tolerate it fine.