To leave or not?

[Inadither]

I've been with DH with a break of a few months before we were married for about 12 years, friends before that. We have x2 DC. I was a bit of a wild child in my 20's and by the time I was ready to settle down it seemed the choices were limited. I did love DH but split with him before we were married as I got fed up with the state of his house and his slobbishness and the fact that he spent more time on his hobbies than he did with me.
We got back together as I missed him and missed being with someone if I'm being brutal. I also only remembered the good stuff after he'd gone. Once I'd made this decision I felt I couldn't muck him about any more and even though I still had doubts we got married. We've had some good times but I seem to spend most of my time wondering whether I love him (or am capable of loving anyone) and if I should leave him. He's difficult to talk to and doesn't want to face up to stuff. It takes me quite a bit of courage to try and talk to him and often discussions are shut down by him. Either that or he'll ask me if I feel better and nothing that we've discussed changes for longer than a couple of days. I go through phases when I feel utterly depressed about our life together and the thought of getting old together and feel like I'm becoming insecure in who I am and don't like myself at all. I think I'm horrible TBH.
When I think about leaving I'm unsure whether it's my state of mind making problems where there aren't or shouldn't be any or whether it's the problems making me feel like this. Which comes first, the problems in our marriage or my state of mind iyswim? He's a decent man but we're hardly having sex and the thought of it makes me want to shudder at the moment. Sex when we've had it is uninspiring and in all our time together he's given me oral once. It got to the point where if he won't give to me, then I won't give to him. He's serially incompetent and I think I notice this all the more because I'd probably like to be too as I'm naturally lazy.
I had a referral for counselling which I've not yet followed up from The GP. I have poor emotional insight though and am worried that I'll talk myself in to leaving when maybe that's not what I want? We have DC and I don't want to mess them up. Need to make the right decision. I don't know what I'm asking. I have no one I feel I can confide in as where we live we have new friends and family I feel would be judgy. I guess I'm just letting out how I'm feeling tonight.

[MakeItRain]

I think firstly you need to follow up the counselling as you sound unsure about what you actually want.
If you decide you want to end your relationship it doesn't make you a bad person. I always think it's better for children to be with separated parents than parents who are unhappy together. (Spoken as someone whose parents "stayed together for the children.)
So don't feel guilty if that's what you do decide to do.