Should I tell her what I really think?

On thursday night my friend Kay broke up with her boyfriend who she had been dating for about two months. She was really unhappy and hardly ever saw or talked to him and when I was with her all she did was complain about him and say it didn't really feel like she was in a relationship with him. She calls me constantly all day friday telling me how she misses him and she can't stop thinking about him. Well I was out of town so I couldn't do anything to take her mind off of him so I suggested she watch movies or get out of the house and go to our other friends house. Well she basically refused to and spent all of friday just sitting there thinking about him and crying. At some point she decided to call and talk to him and he ignored her call, but then called back and somehow they ended up back together and she tells him they broke up because I told her to break up with him. I just got back into town and had lunch with her. She spent the entire lunch telling me it was my fault she broke up with him in the first place and she also was already complaining about him. I basically just sat there during lunch and stared at her because I was mad and couldn't believe she was trying to blame me for her relationship problems. And I never told her to break up with him. I told her to do whatever she thought would make her happy because I didn't like seeing her unhappy. She just texted me and is apparently mad I didn't talk during lunch and she wants to know what I really think about her and her relationship with him. What I really think is it is pathetic she couldn't go one day without him and she didn't even give being single again a chance. I also think it is pathetic she can't take ownership for her actions and instead has to blame it on me when I didn't do anything. I also want to tell her she is too immature for relationships and has no idea what it means to be in love with someone. So should I tell her what I really think or should I just keep my mouth shut?