Dont know what to think!!

Hi all, i could do with some opinions plz.

I was with this guy for about 4 months. Everything was going really well, we was getting on really good and he had even met my kids. Then 2 weeks ago Sunday he had his freinds over to his house for a drink, i was invited over but i couldnt get a babysitter, so we was texting each other all night.
I didnt see him on the Monday because he said he had a hangover and i didnt have any reason to doubt him but still texting each other all day. We arranged that he would come over on the Tuesday evening after the football had finished, he phoned me then to say he wasnt comeing over because he didnt feel to well, i didnt mind and everything was still fine.
I then went over to his house on the Wednsday daytime and the police arrested him for makeing threats to his ex but everything was still the same between us as it always had been, then on Thursday he said he wanted to cool things down because he wanted time on his own because he suffers from depression, but we was still together. I didnt have a problem with that, i just thought him being arrested had scared him a bit and guessed he just needed space.
We was still fine on the Friday and arranged that i would go over to his in the evening if i could get a babysitter, i couldnt so he said he would come to mine after his freind and his freinds ex went home. Later on in the evening he rung to say he wouldnt be over because his freind and his ex was staying the night.
Thats when i thought something was up because his freind was trying to get back with his ex, but he would have come over anyway, his freind is practically liveing with him and has stayed there when he has stayed at mine.
I tried not to think to much about it and make problems up that didnt exist. then last Saturday he says that its over because he wants to be on his own because he cant handle a relationship until he sorts his depression out, but he still wanted to be freinds, it didnt make any sense to me because everything was great until then.
He is now saying that he is with his freinds ex and he got with her the day after he dumped me, i dont know what to think he has never had a nice word to say a bout her and he was trying to get his freind back with her. Ive tried asking him to tell me the truth why he dumped me an got with her less that 24 hours later, all he says is i dont want to talk about it.
There is a part of me that thinks he isnt with her but also a part of me thinks that if he is with her its been going on longer than he recons.
I dont know what to think or how to act, i havent stopped crying and im desperate for answers, which i aint going to get, its like it all changed over night and im not sure why and thats the hardest part.
What do any of you think?
Any opinions or advice to get over this as quickly as poss will b really appreciated.
Thanx

I think he was using the "im not ready for a relationship" line as an excuse. I guess the reason he was a bit off in that week was because he was preparing to get back with his friend's ex, and being a bit distant towards you in an attempt to lessen the hurt when he dumps you. You say that you feel like everything has changed over night..but you had to have suspected something when he was brushing you off in that week and getting arrested for harassing his ex. I don't think his head or heart for that matter were in the relationship to begin with..a guy that truly loves you would want to be with you over his friend (who you said stays over nearly all the time). seems like he was just making excuses..wouldn't waste my time on someone like that. don't ever cry over someone who isn't crying over you..he should be at least a little hurt if he loved you in the first place. so chin up and smile for your kids!!

I think since you two were only together for 4months, it shouldn't be that hard for you to just let him go, take sometimeout for just you. heal from this. Try not to think about it anymore. You're just torturing yourself for no reason!!!!! He has serious mental issues anyway.... Go find someone who's healthy!!!!