Dating a widower

So I have been with my partner for 11 months, its coming upto a year that he lost his wife. I cared for his wife in a care home for 7 months before she passed, everyone at the home become close to him as he came every single day. After she passed away we stayed in touch, became close and started dating. It can be very challenging at times, especially at the moment as its coming upto her first anniversary. He is a massive part of my life, met all my most important people in my life, he has a great relationship with my children, 22, 19 and 12. But…I am pretty much still a secret in his life apart from me meeting his dad twice, his son knows about us and very briefly met at the beginning, and a couple of friends know, but other than that, his side of things are pretty much separate. Im just wondering if anyone has been in a similar situation.? Im in love with this man, and I know he cares for me very deeply, but im scared