Friend moved in with me and I need her to pay me rent. I'm just married in my new house?

Me and my husband are both 45yrs old. We just got married 6 months ago. Until this point we lived wtih our moms and saved EVERY PENNY since we started working 22yrs ago. We did not even have a party for our wedding, just a small meal in a friends cafe and invited just our parents and immediate family. We just HATE spending money. Now we have our own home , with 3 bedrooms. We have decided that although the mortgage is almost paid ( we basically could buy it outright from our savings and generous cash gifts from family). So we do not have a mortgage. We have decided that we will rent out two rooms in our house as an investment for 5 yrs. We just pocket the money. However, my friend who lived abroad has moved back to this town. She lost her husband 4 months ago and wants to come home. She asked could she move in with us for month or two until she finds her feet. She also has a 5 yr old boy. They are taking up a room in our house. This is their second month. First month i said she only had to pay the bills and cook our dinner - rent free. Now i want rent for the room and i would prefer if she stopped her kid climbing all over my couch (which still has the wrapper on it as we are that particular and precious of it). How do i bring this up? I'm not even sure she has her finances in order.