Is my depression sabotaging my relationship?

This post has been incredibly hard for me to write.

I don't open up about this topic to many people, through fear of being misunderstood or judged and maybe because writing some of it down makes it feel a bit too real. I'd rather ignore some of these feelings because life is just easier that way.

I'm writing it though, because I think to continue down the recovery path I need to get it out. I'm hoping that some of you, even one of you, may have the same problem, that it may be connected to my depression and isn't just my own personal bit of crazy.

Through my entire life, including but not limited to bouts of depression, I find that my emotions can sometimes switch off and on like a light switch.

Without explanation I can go from being so happy it borders on hyper, to so sad I am, literally, daydreaming about suicide. From the nicest, kindest person, to an angry bitch, saying cruel and spiteful things at the drop of a hat.
Or from feeling immense love, to feeling complete indifference.

It's that last one that I want to talk about. How I feel about my husband has and continues to change constantly. I'm not just talking about normal mood swings, or days when he gets on my nerves more than usual, I'm talking about being utterly convinced I am in love and happy with him one minute, to not wanting him anywhere near me and daydreaming about being on my own the next.

It works the other way too, I can go through months of feeling like we're just not right together, desperate to avoid him touching me, wishing I could escape etc etc, to suddenly, with the flick of some internal switch, back to feeling loving and affectionate towards him. Safe and happy in the knowledge that we're together, and feeling immensely guilty for how I treated him during other periods.

I can't stop the down periods from happening, I've tried everything other the years. And it's happened in previous relationships too - my first love I broke up with during a down period then massively regretted it and could never get him back.

The constant changes over the years have, understandably, taken their toll on our marriage, and on me.
Because one emotion never stays, I can't identify what I need to do to make myself happy. If I left during a down period and then the feelings bounced back like they always do, I will be left with a broken marriage, kids who don't live with their dad and lets face it a spiral of severe depression.
But staying. Staying, puts him and me through these constant up and downs. Months without intimacy or affection, two people just living together, raising there kids and getting along perfectly well, but with no warmth between them. I'm worried it's going to eventually push him away. That he will get fed up with the down periods, and leave.

How do I identify which feeling is the real one?

Part of me is scared to know in case it means my future will be different to what I'd always planned, in case it means that my kids won't have the family life I so dearly wanted for them. But another part of me is hopeful that good periods could win, if only my mind would let them. 

Is my depression sabotaging my relationship?

Depression can be such a negative drain on everything good in life, and I wonder if, in the down periods, the depression is there, pointing out anything and everything negative, making me feel lethargic and uninterested, and encouraging me to seek solitude?

Please know, my husband is kind, caring and supportive. He is more involved with the kids than most parents I know. He's an amazing, loving, dad and extremely selfless. None of this should be read as a reflection on him, I can't emphasise that enough.
I'm sorry this post is rather disjointed and seems to have little point to it. I guess what I'm really trying to do, is face up to things I keep burying and ignoring because I don't know how to explain or deal with them.

It's part of my journey, I suppose, to work on the route cause of my constant battles with depression and anxiety. If only I knew what to do next.....