Sex am I gay

How many other girls on here have have fantasied about another female and been straight. I have always enjoyed looking at other girls but it was only when I started getting anonymous texts from some girl I work with telling me she couldn’t say who she was but really wanted me . I’m straight but this drove me mad I even got caught masturbating by my husband although I still to this day won’t admit it. I’m 40 odd and it’s the first time I have really masturbated also a question on here has had my mind working overtime about a threesome I would love to try it with another woman. Is this normal