Does anyone else get accused?

My boyfriend just accused me of cheating on him, due to being on my phone all the time. Little does he know it's because I'm planning on asking him to marry me and I have been trying to find the right set of rings and the right way to ask. He made me so upset thinking I would do something like that instead of telling him what I was really doing I just sat there and took it. I'm a stay at home mom of 2 boys both ages 4 and 10 months, not to mention my 4 yr old has special needs so I spend all my time catering to them. I have no time to cheat. I just wanted to surprise him now I feel like if I go thru with it I'm going to marry a guy that can't trust me, that and I don't want him to feel guilty for yelling at me.....