Massage massage massage!!!! Its sooo important!
I had a tight scar too, and everytime we tried to DTD it ended in tears. So scary, and just yuck, and totally meant I wasn't relaxed or interested.
Lube did help alot.
But - the real breakthrough for me was when I got AF back quite quickly (about 8w??) even though I was fully breastfeeding. Cause I'm pretty active with netball and all, I used tampons after teh second cycle, and it hurt like hell, but within about 2-3 months it was a different story. Inserting the tampon must have massaged the scar in some way, and it just broke down all the scar tissue. I am 100% convinced you could do this yourself through massage.
I've just checked with my midwife re my scar tearing in the next labour, and she gave me a very detailed pamphlet on perinium massage. It looks like the goer.

Hopefully something like this will make a big difference for you!