Very Confused Of My Feelings

Anonymus Please..... Hello IMs please no judgment just advice or experience please .. ill explain a little first I have been in a relationship for 22 years but over the past 3yrs we disconnected due to alcohol and drugs and emotional abuse I have 3 children to late teens and a surprise baby who is a toddler in the last 5 years I have has sex only 3 times .we have now separated , I know a lot of people to say hi to but I only had one very close best friend I ardour her children as she did mine , 12 months ago my dear sweet friend passed away in a accident with her at the time her son who survived so you can imagine what he went through she left behind 4 children and a husband , we all are grieving its hard , I spend as much spare time with her kids as I can , but just recently with the firsts , bdays , Xmas ect its been tough ..
Now I'm confused her husband just recently was talking to me more openly and hugs ect I was reading his body language and its really open and direct and for the first time in my life I have this strong urge to have sex with him I don't know where this has come from I'm so confused into why I feel like this I'm scared to approach this with him I don't want this to change the relationship I have with the kids ect ..but I'm so lonely and he is too and I love his wife as he does to .....I don't want a relationship just sex ...please is this normal ..TIA