Emilykate, the title of the post should give you some hope...many, many women on this site have experienced awful moments in their lives and have struggled through and come out the other side. Nowcemsi is proof that the light at the end of the tunnel will shine.
Decsions made alone are really hard to deal with if you have opposition but you made it for all the right reasons and should never feel guilty about it. Your focus now is regaining your health and hanging on to your children. You should stay and live in the family home with them. You do need to see a solicitor to have your rights explained, I managed to divorce my husband on the strength of one, half hour session costing Ł25. I told the solicitor to speak fast, tell me all the facts and put it in wrting when he sent the bill. He did exactly that and I am very grateful.

Your husband is clearly hurting and angry and may never calm down enough to see why you did what you did, but it's done now and if he says it's over then as I said, you must focus on your health and children.
Many wise women will be on this forum who will undoubtably offer sensible advice and you must never be afraid to ask for help.
Above all - NEVER feel guilty. B strong.
Sending big hug.