Struggling with my sexuality

I’ve been with my boyfriend for 3 and a half years and we have a 15 month old son together...I’ve always felt bi but my family is strictly religious and against it so I did what everyone expected me to do by being with a guy...so I suppressed these feelings as much as I could until recently when my 16 year old neice came out as bi,..at 35 you would think that i should have had the courage to do this on my own and not be inspired by a 16 year old girl...I love my boyfriend more than anything and want to be with him but I love girls as well...I want to bring up the idea of adding a female to our relationship but I don’t know how to start the conversation cuz I’m scared of loosing him and our son