Won't 'advise' because I'm not in a position to, but I'll tell you what happened with me and you can take from it what you will....
Me and a guy were good pals. Knew his Mrs for the same amount of time, lovely girl.
She was his first love, in his eyes 'the one'. They split up as they were very young when they were together.
She went to uni, moved on, had boyfriends etc....
He joined the marines, moved on, had girlfriends etc...
Me and him used to meet up regularly, get drunk, moan about women etc.
Him and her had the same very tight friendship group from when they were kids and so saw each other quite frequently. Just as pals, most of the time while they had their own different partners, and still got on very well.
One night I go out with the pair of them and me and her have a 'spark'. Never really thought of her in that light before.
She texts me for drinks because we're both single, both bored and it's fun to go drinking with someone of the opposite sex.
Obviously after a few 'not really dates' we get to the point where we kinda want to start seeing each other. We both decide we shouldn't for our mutual friends feelings, but still like each other.
Eventually we decide that they'd been split up for over five years, had both had different partners since and why shouldn't we? So we did.
She tells him, he gets in a strop and doesn't want to be pals with either of us.
I can live with that, all's fair in love and war and all that.....
She doesn't feel so good about it, they have close mutual friends and it's all a bit difficult, but she's chosen me and she didn't regret it.....
A shame but it is what it is.....
Then a year or so later, the poor sod gets killed by his brother in a car crash, big genuine tragedy, very sad for everyone.
Our relationship has nothing to do with that crash, but because of the bad feeling prior to it happening she now feels super guilty. She clearly resents me because of the bad feeling between her and him that she now can't undo.
I can't really be around her friends because like I say, they were close mutual pals of him and her so they chose to blame me for the bad feeling between him and her, which again, isn't a problem to me, I don't like them anyway, but it's a problem to her which is another barrier in our relationship.
All in all it's a very griefy and awkward situation and sadly made all the worse by the tragedy.
There is no 'moral' to this story, it is what it is, and if it's useful to you then I'm glad it is.