I was in the same position last year wherein I had a full time family interested in starting but I had a part time after school child taking up that spot. Like you, some times she came 2-3 times per week and sometimes, zero times during a week. I felt really bad because like you, it was my daughter's friend and I also really loved the parents. I was just completely honest with her and gave her plenty of notice as you intend to...I told her that I love having her child around but this a a complete business move "for financial reasons". I actually got stressed out so much about it leading up to giving her notice...but then once I bit the bullet and went through with it, it went way more smoothly than what I imagined could happen (I was imagining conflict, lol) and I felt much better afterwards!! It's hard, but everything will be ok