NC and will try not to drip feed, will be a long one (sorry) 
I need help giving my head a wobble to put things into perspective.
Been with DP for 16yrs (got together as teens, first love etc), DC, DP is a couple of yrs older than me.
Background : Throughout high school I was singled out by a group of boys (one in particular) who would give me unwanted attention, grabbing and touching me inappropriately, then would spread false rumours about me of a sexual nature. Got together with DP during this time.
Met DP through group of friends outside of school, and again the boys seemed to single me out grabbing and touching me, but I began to accept it as the norm. DP was my safety net as it rarely happened when he was around.
At 15, DFriend(17) begged me to go with her to meet her xbf (first I'd heard of him) and try to help her win him back. Reluctantly agreed, but it turned out df's ex was 26 and it was going to be a house party consisting of me, df, df's ex, 2 men (early 20's) and another girl(18/19). Felt uncomfortable but caved into pressure to stay. Had a drink then it's all rather hazy. Next day Df told DP I'd cheated on him at party. DP was hurt and I denied it but he long held onto the belief that if I couldn't remember I probably did cheat or I'm an epic liar.
Few yrs passed, moved in together, followed by pfb, but the mistrust was still there. I felt pressured into performing sexually, if not DP would bring up the past, calling me names and blaming me. This was mainly when he was drunk and angry. Eg. A few times he would punch walls, doors etc, once he pinned me against the wall by my throat then followed me around the house slapping his belt against his hand making me think he was going to hit me. He never did hit me and never has, although I'll hold my hands up and admit that I've slapped him (completely wrong of me and no justification at all). The DC haven't witnessed any of this.
He became addicted to porn. At first I accepted it, but it became a problem when he began to hide it, watching excessively, used in place of having RL sex, watching more extreme stuff, had no interest in having sex with me but a few times I woke to find him having sex with me while I slept. During this time I also found out he'd been chatting to a woman he met online and they had exchanged phone numbers, although they hadn't met irl.
We worked through it all, then a short time later we where having piv sex and he got behind me. The next thing i know he was trying to have anal sex with me. He knew I didn't/don't like anal so I moved forward slightly and reminded him I didn't like it. I ended up flat on the bed with his weight on my back and he did it anyway while I cried into my pillow, so as not to wake DC. He apologised, swore it wouldn't happen again etc. I forgave him.
Fast forward to now: For the past few yrs our relationship has been good, although I have felt that DP can be dismissive of me emotionally. Months ago DP told me he wasn't satisfied with our sex life. We put in the effort and things improved, but suddenly the sex stopped, he became moody and distant. He's started seeing a counsellor for depression, so I put it all down to this. But I had a niggling doubt so asked him outright if he was chatting to someone again and he denied it. I snooped. Turns out it's the porn again. It's brought everything from the past back, especially since I found he's been using search terms like bad anal and painful.
Confronted him and he admitted it has become an addiction again and he's concerned at how fast it's spiraling out of control. He says he's discussed it with his counsellor, he understands why it's a problem for me and accepts that he hasn't behaved well in the past. He tells me he loves me and wants me to forgive and forget as he's apologised. But I'm struggling with it all, especially as I feel he's been emotionally distant from me for a good few yrs, although the rest has been good.
He says counselling has made him realise his MH is the reason that he's incapable of showing me love and affection as he doesn't feel any emotion or care about anyone/anything apart from me and DC. I'm struggling to accept this explanation as he thankfully still shows the DC love and affection whereas the only emotion towards me seems to be anger and irritation and only kindness when it involves sex.
Last night we argued about it again (my fault, I was angry and brought it up). During the argument I tried to march past DP and go upstairs but he pulled me back with my arm, got up in my face and began pushing me. This is the only time, apart from the one time in the past, that I've felt physically threatened by him. He says he didn't hit me and wasn't going to. He acted that way because he was scared that I would go upstairs, wake the DC up and tell them everything.
He also says I'm not being supportive of his MH and that I'm acting as if he's had a RL affair.
I feel hurt and resentful but I can't help but think he's right that I'm overreacting and being unfair towards him. I love him a lot and feel that I'm responsible because of my past actions and also that I should be more supportive and understanding of his MH. But I'm just struggling to get over it and give him the love and support.