C - First and foremost, I am sorry for the pain and heartache you are going through and I understand so well that as crazy as it sounds - the strength you need to STAY is often greater than the strength required to move on if the marriage falls apart.
You have to allow yourself time, space, care to heal! You cannot allow yourself to be manipulated by his manic ups and downs. You love him - I know. And I do have faith that 10 years down the road, if you are able to get through this your marriage will be stronger and you will be glad you were able to stay together. But this road is tough. Find someplace that you can go for quiet and meditation or prayer and allow yourself to feel what you need to feel. Do this as often as you need. Unfortunately, if you can prevent him from seeing this it is probably better as the reality is he is not yet stable.
I know this path very well. And although my X was unable to kick his habit - in hindsight and in working with counselors I know that the work I was doing while "sticking it out" was the right work.
Thoughts and prayers are with you.
IB
M-48/XH-48 M=25/T=28 years Ds-24,22/S-18 D - 3/11 A Day at a Time