I had a lengthy separation from MrsD, who I've now been back with for a few years.
The only thing I'd chip in with is about Relate. The counsellor you see first time around may, or may not, be any good. We saw one guy for a year before I walked out. It wasn't his fault, but he allowed my wife to run rings around him, alienated me and certainly did nothing for the relationship.
When we were experimenting with getting back together, we saw a different guy (not through Relate) who was much, much better. He called bullsh*t on a lot of things my wife told him, and was far better at getting into her head. I strongly suspect if we had seen the right counsellor in the first place we could have made better progress.
It's very hard to have a sane conversation with someone about whether the horrendous marriage counselling session you just endured was horrendous because you hate one another or because the counsellor is a pillock, but it's one to bear somewhat in mind.