How do I overcome a lying partner?

I am in love with a man that I use to date years ago. We managed to get back together after 4 years & we have always loved each other. We have been friends for years & during the times that I was dating someone else, he was the friend to give me good, sound, concrete advice. The guy I use to date was addicted to porn & I had a hard time dealing with it. While confiding in my now present boyfriend, he knew how hurt I felt about the situation & how betrayed I felt. While I don't think there is anything horribly wrong with lookin at porn, I think it reaches another level if they are paying for it. Well I ended up leaving the old boyfriend for multiple reasons but I'm now in a serious relationship with my "advisor". I've always found him to be the most upfront, honest, sincere person. He has always been this upfront type of guy who gives people advice & is a very strong headed individual overall. This is what attracted me to him in the first place. We've been dating now for almost a year & things were good until I started to notice he speaks with ALOT of different women. Now I know that he has always had a lot of female friends & I don't really care about that. After all, how can I be upset with him when I use to be one of those friends that he gave advice to. Well, I've run into situations that I found to be deceiving. He's done the whole romantic thing with me...kisses me, tells me how lucky he is to have a beautiful woman next to him, calls me baby and my love, sings to me & all those sweet Little gestures. Well I came across a text message on his phone, yes I'm guilty of snooping, & found that he was talking to someone in the same way that he speaks with me! He even went so far as to send this girl a picture of himself along with the SAME SONG he's dedicated to me! And the sad thing is that he sent me the same picture & song two days prior. He talks with a lot of his ex's & his phone rings NON STOP at any hour of the day or night! Now okay, I had to say to myself, is this me being insecure? Do I have low self esteem? or is there clearly something wrong with this picture. I don't think there is anything wrong with a man having female friends & I guess some men can be chatty cathy's. I don't care about that but what I do care about is the level of respect he has for me. I give 100% of myself & I care for his kids he has living with him at home, & I feel that I am a GREAT woman. I am divorced & even my ex husband says that he let a good woman get away. The reason I am divorced is due to infidelity but that's another story. He has gone so far as to discuss marriage with me, merging our finances, asked me to come live with him & we are even trying to get pregnant. So all of these things have happened & its made me feel that this many REALLY wants to be with me & is being true to me. As time has gone on, I have come across little things here and there that has made me question his loyalty to me. He's a flirt! I think he loves to receive attention from other woman. He is a good looking guy & he tells me all the time that he would never do anything to hurt this relationship & that I'm the one he wants for the rest of his life. Sure we've had quite a few arguments & we are still learning each other, but it makes it hard to trust someone when you've been lied to. When confronted about the girl he sent messages to, he claims she is just a friend & he's never even met her in person. To a degree, I have to understand that we all have friends, some close, some far, some that become really good friends. After all, I have friends I call honey & baby too. But he told me that there was nothing going on & that was that. Problem is that now when he calls me "his love" or "baby", they don't carry any weight. I don't feel that I stand out from all the rest. He won't even put that he is in a relationship on his facebook page and his excuse is that "I'm here with you, what does it matter, I don't care about facebook". So I've had to suck this up and just let it be. Well now here is another problem, He left his computer up & asked me to take a look at something on his computer. While doing so, I came across an email that was a receipt for payment. Here's the bomb...it was for a PORN SITE! He has a PAID SUBSCRIPTION!! I've talked to him about things I've found on his computer in the past and no I was not snooping, but he had a screen saver come on one time & it was of photos..of NAKED WOMEN! So I'm staring to feel that there is a secret life he is living on the internet. His response is, it's nothing, I love you, I'm with you, stop going thru my computer looking for things, what I do on my computer is my business. Well those are not the words a woman wants to hear from the man she plans to spend her life with. I am finding it hard to trust anything he says and I refuse to